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  • Business Intelligence avec SQL Server 2008 R2 de Sébastien Fantini, critique par Celinio Fernandes

    Bonjour La rédaction de DVP a lu pour vous l'ouvrage suivant: Business Intelligence avec SQL Server 2008 R2 de Sébastien Fantini paru aux Editions ENI [IMG]http://images-eu.amazon.com/images/P/274605566X.08.LZZZZZZZ.jpg[/IMG] Citation: Ce livre sur la Business Intelligence (BI) avec SQL Server 2008 R2, s'adresse à tous les membres d'une équipe décisionnelle : chef de projet, architecte, développeur ETL,...

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  • Les 11 lois du marketing créatif, de Katalin Berenyi, critique par Youghourta Benali

    Bonjour, La rédaction de DVP a lu pour vous l'ouvrage suivant: Les 11 lois du marketing créatif de Katalin Berenyi [IMG]http://images-eu.amazon.com/images/P/2212549997.08.LZZZZZZZ.jpg[/IMG] Citation: De l'expérience de Katalin Berenyi est née cet ouvrage, véritable condensé d'énergie pour remporter de grands succès et relever les défis marketing de demain : une méthode basée sur les "pas de côté&qu...

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  • Des serveurs du site officiel de PHP ont été compromis, un nouveau coup dur dans le domaine de la sécurité

    Des serveurs du site officiel de PHP ont été compromis, un nouveau coup dur dans le domaine de la sécurité Si vous avez essayé de vous connecter sur le site officiel de PHP avant hier, vous aurez sans doute lu le message d'alerte indiquant que le site contient un logiciel malveillant. La découverte a été faite jeudi dernier par le service de navigation sécurisée de Google qui aide les Chrome, Firefox, et Safari à bloquer automatiquement les sites dont les serveurs ont été infectés par des...

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  • Clustered MSDTC

    - by niel
    Hi I'm setting up a SQL cluster (SQL 2008), Windows 2008 R2. I enable the network access on local dtc and then create a DTC resource in my cluster . the problem is that when i start up the resource it does nto pull through my settings to enable network access. the log shows this: MSDTC started with the following settings: Security Configuration (OFF = 0 and ON = 1): Allow Remote Administrator = 0, Network Clients = 0, Trasaction Manager Communication: Allow Inbound Transactions = 0, Allow Outbound Transactions = 0, Transaction Internet Protocol (TIP) = 0, Enable XA Transactions = 0, Enable SNA LU 6.2 Transactions = 1, MSDTC Communications Security = Mutual Authentication Required, Account = NT AUTHORITY\NetworkService, Firewall Exclusion Detected = 0 Transaction Bridge Installed = 0 Filtering Duplicate Events = 1 where when i restart the local dtc service it says this: Security Configuration (OFF = 0 and ON = 1): Allow Remote Administrator = 0, Network Clients = 1, Trasaction Manager Communication: Allow Inbound Transactions = 1, Allow Outbound Transactions = 1, Transaction Internet Protocol (TIP) = 0, Enable XA Transactions = 1, Enable SNA LU 6.2 Transactions = 1, MSDTC Communications Security = No Authentication Required, Account = NT AUTHORITY\NetworkService, Firewall Exclusion Detected = 0 Transaction Bridge Installed = 0 Filtering Duplicate Events = 1 settings on both nodes in teh cluster is the same. I have reinstalled and restarted to many times to mention. Any ideas ?

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  • Common Live Upgrade problems

    - by user12611829
    As I have worked with customers deploying Live Upgrade in their environments, several problems seem to surface over and over. With this blog article, I will try to collect these troubles, as well as suggest some workarounds. If this sounds like the beginnings of a Wiki, you would be right. At present, there is not enough material for one, so we will use this blog for the time being. I do expect new material to be posted on occasion, so if you wish to bookmark it for future reference, a permanent link can be found here. Live Upgrade copies over ZFS root clone This was introduced in Solaris 10 10/09 (u8) and the root of the problem is a duplicate entry in the source boot environments ICF configuration file. Prior to u8, a ZFS root file system was not included in /etc/vfstab, since the mount is implicit at boot time. Starting with u8, the root file system is included in /etc/vfstab, and when the boot environment is scanned to create the ICF file, a duplicate entry is recorded. Here's what the error looks like. # lucreate -n s10u9-baseline Checking GRUB menu... System has findroot enabled GRUB Analyzing system configuration. Comparing source boot environment file systems with the file system(s) you specified for the new boot environment. Determining which file systems should be in the new boot environment. Updating boot environment description database on all BEs. Updating system configuration files. Creating configuration for boot environment . Source boot environment is . Creating boot environment . Creating file systems on boot environment . Creating file system for in zone on . The error indicator ----- /usr/lib/lu/lumkfs: test: unknown operator zfs Populating file systems on boot environment . Checking selection integrity. Integrity check OK. Populating contents of mount point . This should not happen ------ Copying. Ctrl-C and cleanup If you weren't paying close attention, you might not even know this is an error. The symptoms are lucreate times that are way too long due to the extraneous copy, or the one that alerted me to the problem, the root file system is filling up - again thanks to a redundant copy. This problem has already been identified and corrected, and a patch (121431-58 or later for x86, 121430-57 for SPARC) is available. Unfortunately, this patch has not yet made it into the Solaris 10 Recommended Patch Cluster. Applying the prerequisite patches from the latest cluster is a recommendation from the Live Upgrade Survival Guide blog, so an additional step will be required until the patch is included. Let's see how this works. # patchadd -p | grep 121431 Patch: 121429-13 Obsoletes: Requires: 120236-01 121431-16 Incompatibles: Packages: SUNWluzone Patch: 121431-54 Obsoletes: 121436-05 121438-02 Requires: Incompatibles: Packages: SUNWlucfg SUNWluu SUNWlur # unzip 121431-58 # patchadd 121431-58 Validating patches... Loading patches installed on the system... Done! Loading patches requested to install. Done! Checking patches that you specified for installation. Done! Approved patches will be installed in this order: 121431-58 Checking installed patches... Executing prepatch script... Installing patch packages... Patch 121431-58 has been successfully installed. See /var/sadm/patch/121431-58/log for details Executing postpatch script... Patch packages installed: SUNWlucfg SUNWlur SUNWluu # lucreate -n s10u9-baseline Checking GRUB menu... System has findroot enabled GRUB Analyzing system configuration. INFORMATION: Unable to determine size or capacity of slice . Comparing source boot environment file systems with the file system(s) you specified for the new boot environment. Determining which file systems should be in the new boot environment. INFORMATION: Unable to determine size or capacity of slice . Updating boot environment description database on all BEs. Updating system configuration files. Creating configuration for boot environment . Source boot environment is . Creating boot environment . Cloning file systems from boot environment to create boot environment . Creating snapshot for on . Creating clone for on . Setting canmount=noauto for in zone on . Saving existing file in top level dataset for BE as //boot/grub/menu.lst.prev. Saving existing file in top level dataset for BE as //boot/grub/menu.lst.prev. Saving existing file in top level dataset for BE as //boot/grub/menu.lst.prev. File propagation successful Copied GRUB menu from PBE to ABE No entry for BE in GRUB menu Population of boot environment successful. Creation of boot environment successful. This time it took just a few seconds. A cursory examination of the offending ICF file (/etc/lu/ICF.3 in this case) shows that the duplicate root file system entry is now gone. # cat /etc/lu/ICF.3 s10u8-baseline:-:/dev/zvol/dsk/panroot/swap:swap:8388608 s10u8-baseline:/:panroot/ROOT/s10u8-baseline:zfs:0 s10u8-baseline:/vbox:pandora/vbox:zfs:0 s10u8-baseline:/setup:pandora/setup:zfs:0 s10u8-baseline:/export:pandora/export:zfs:0 s10u8-baseline:/pandora:pandora:zfs:0 s10u8-baseline:/panroot:panroot:zfs:0 s10u8-baseline:/workshop:pandora/workshop:zfs:0 s10u8-baseline:/export/iso:pandora/iso:zfs:0 s10u8-baseline:/export/home:pandora/home:zfs:0 s10u8-baseline:/vbox/HardDisks:pandora/vbox/HardDisks:zfs:0 s10u8-baseline:/vbox/HardDisks/WinXP:pandora/vbox/HardDisks/WinXP:zfs:0 Solaris 10 9/10 introduces new autoregistration file This one is actually mentioned in the Oracle Solaris 9/10 release notes. I know, I hate it when that happens too. Here's what the "error" looks like. # luupgrade -u -s /mnt -n s10u9-baseline System has findroot enabled GRUB No entry for BE in GRUB menu Copying failsafe kernel from media. 61364 blocks miniroot filesystem is Mounting miniroot at ERROR: The auto registration file does not exist or incomplete. The auto registration file is mandatory for this upgrade. Use -k argument along with luupgrade command. autoreg_file is path to auto registration information file. See sysidcfg(4) for a list of valid keywords for use in this file. The format of the file is as follows. oracle_user=xxxx oracle_pw=xxxx http_proxy_host=xxxx http_proxy_port=xxxx http_proxy_user=xxxx http_proxy_pw=xxxx For more details refer "Oracle Solaris 10 9/10 Installation Guide: Planning for Installation and Upgrade". As with the previous problem, this is also easy to work around. Assuming that you don't want to use the auto-registration feature at upgrade time, create a file that contains just autoreg=disable and pass the filename on to luupgrade. Here is an example. # echo "autoreg=disable" /var/tmp/no-autoreg # luupgrade -u -s /mnt -k /var/tmp/no-autoreg -n s10u9-baseline System has findroot enabled GRUB No entry for BE in GRUB menu Copying failsafe kernel from media. 61364 blocks miniroot filesystem is Mounting miniroot at ####################################################################### NOTE: To improve products and services, Oracle Solaris communicates configuration data to Oracle after rebooting. You can register your version of Oracle Solaris to capture this data for your use, or the data is sent anonymously. For information about what configuration data is communicated and how to control this facility, see the Release Notes or www.oracle.com/goto/solarisautoreg. INFORMATION: After activated and booted into new BE , Auto Registration happens automatically with the following Information autoreg=disable ####################################################################### Validating the contents of the media . The media is a standard Solaris media. The media contains an operating system upgrade image. The media contains version . Constructing upgrade profile to use. Locating the operating system upgrade program. Checking for existence of previously scheduled Live Upgrade requests. Creating upgrade profile for BE . Checking for GRUB menu on ABE . Saving GRUB menu on ABE . Checking for x86 boot partition on ABE. Determining packages to install or upgrade for BE . Performing the operating system upgrade of the BE . CAUTION: Interrupting this process may leave the boot environment unstable or unbootable. The Live Upgrade operation now proceeds as expected. Once the system upgrade is complete, we can manually register the system. If you want to do a hands off registration during the upgrade, see the Oracle Solaris Auto Registration section of the Oracle Solaris Release Notes for instructions on how to do that. Technocrati Tags: Oracle Solaris Patching Live Upgrade var sc_project=1193495; var sc_invisible=1; var sc_security="a46f6831";

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  • Security Access Control With Solaris Virtualization

    - by Thierry Manfe-Oracle
    Numerous Solaris customers consolidate multiple applications or servers on a single platform. The resulting configuration consists of many environments hosted on a single infrastructure and security constraints sometimes exist between these environments. Recently, a customer consolidated many virtual machines belonging to both their Intranet and Extranet on a pair of SPARC Solaris servers interconnected through Infiniband. Virtual Machines were mapped to Solaris Zones and one security constraint was to prevent SSH connections between the Intranet and the Extranet. This case study gives us the opportunity to understand how the Oracle Solaris Network Virtualization Technology —a.k.a. Project Crossbow— can be used to control outbound traffic from Solaris Zones. Solaris Zones from both the Intranet and Extranet use an Infiniband network to access a ZFS Storage Appliance that exports NFS shares. Solaris global zones on both SPARC servers mount iSCSI LU exported by the Storage Appliance.  Non-global zones are installed on these iSCSI LU. With no security hardening, if an Extranet zone gets compromised, the attacker could try to use the Storage Appliance as a gateway to the Intranet zones, or even worse, to the global zones as all the zones are reachable from this node. One solution consists in using Solaris Network Virtualization Technology to stop outbound SSH traffic from the Solaris Zones. The virtualized network stack provides per-network link flows. A flow classifies network traffic on a specific link. As an example, on the network link used by a Solaris Zone to connect to the Infiniband, a flow can be created for TCP traffic on port 22, thereby a flow for the ssh traffic. A bandwidth can be specified for that flow and, if set to zero, the traffic is blocked. Last but not least, flows are created from the global zone, which means that even with root privileges in a Solaris zone an attacker cannot disable or delete a flow. With the flow approach, the outbound traffic of a Solaris zone is controlled from outside the zone. Schema 1 describes the new network setting once the security has been put in place. Here are the instructions to create a Crossbow flow as used in Schema 1 : (GZ)# zoneadm -z zonename halt ...halts the Solaris Zone. (GZ)# flowadm add-flow -l iblink -a transport=TCP,remote_port=22 -p maxbw=0 sshFilter  ...creates a flow on the IB partition "iblink" used by the zone to connect to the Infiniband.  This IB partition can be identified by intersecting the output of the commands 'zonecfg -z zonename info net' and 'dladm show-part'.  The flow is created on port 22, for the TCP traffic with a zero maximum bandwidth.  The name given to the flow is "sshFilter". (GZ)# zoneadm -z zonename boot  ...restarts the Solaris zone now that the flow is in place.Solaris Zones and Solaris Network Virtualization enable SSH access control on Infiniband (and on Ethernet) without the extra cost of a firewall. With this approach, no change is required on the Infiniband switch. All the security enforcements are put in place at the Solaris level, minimizing the impact on the overall infrastructure. The Crossbow flows come in addition to many other security controls available with Oracle Solaris such as IPFilter and Role Based Access Control, and that can be used to tackle security challenges.

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  • Execution time in nano seconds and related issues

    - by anup
    Hi All, I am using the following code to compute execution time in milli-secs. struct timespec tp; if (clock_gettime (CLOCK_REALTIME, &tp) == 0) return ((tp.tv_sec * 1000000000) + tp.tv_nsec); else return ; Can you please tell me whether this is correct? Let's name this function comptime_nano(). Now, I write the following code in main() to check execution times of following operations. unsigned long int a, b, s1, s3; a = (unsigned long int)(1) << 63; b = (unsigned long int)(1) << 63; btime = comptime_nano(); s1 = b >> 30; atime = comptime_nano(); printf ("Time =%ld for %lu\n", (atime - btime), s1); btime = comptime_nano(); s3 = a >> 1; atime = comptime_nano(); printf ("Time =%ld for %lu\n", (atime - btime), s3); To my surprise, the first operation takes about roughly 4 times more time than the second. Again, if I change the relative ordering of these operations, the respective timings change drastically. Please comment...

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  • Various asp controls in a ASP.NET page

    - by Filipe Costa
    Hello. I am creating a products page, where the user selects an option in a radiobuttonlist for example, and then a control with the various options of that product appears in a placeholder or in a div when on of the radiobuttons is selected. At the moment this is the code: aspx: <form runat="server"> <asp:CheckBoxList ID="Lentes" runat="server" OnClick="EscolheLentes"> <asp:ListItem Value="LU"> Lentes Unifocais </asp:ListItem> <asp:ListItem Value="LP"> Lentes Progressivas </asp:ListItem> </asp:CheckBoxList> <asp:PlaceHolder runat="server" ID="PHLentes"></asp:PlaceHolder> </form> aspx.vb: Protected Sub EscolheLentes() Dim ControlLente As Control If (Me.Lentes.Items.FindByValue("LU").Selected) Then ControlLente = LoadControl("LentesUnifocais.ascx") ElseIf (Me.Lentes.Items.FindByValue("LP").Selected) Then ControlLente = LoadControl("LentesProgressivas.ascx") End If Me.PHLentes.Controls.Add(ControlLente) End Sub Need to use some ajax to load the control right? Am i going in the right direction? Thanks.

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  • Are file access times not properly maintained in Mac OS X?

    - by Ether
    I'm trying to determine how file access times are maintained by default in Mac OS X, as I'm trying to diagnose some odd behaviour I'm seeing in a new MBP Unibody (running Snow Leopard, 10.6.2): The symptoms (drilling down to the specific behaviour that seems to be causing the issue): mutt is unable to switch to mailboxes which have recently received new mail mail is delivered by procmail, which updates the mtime of the mbox folder it is updating, but does not alter the atime (this is how new mail detection works: by comparing atime to mtime) however, both the mtime and atime of the mbox file is getting updated Through testing, it does not appear that atimes can be set separately in the filesystem: : [ether@tequila ~]$; touch test : [ether@tequila ~]$; touch -m -t 200801010000 test2 : [ether@tequila ~]$; touch -a -t 200801010000 test3 : [ether@tequila ~]$; ls -l test* -rw------- 1 ether staff 0 Dec 30 11:42 test -rw------- 1 ether staff 0 Jan 1 2008 test2 -rw------- 1 ether staff 0 Dec 30 11:43 test3 : [ether@tequila ~]$; ls -lu test* -rw------- 1 ether staff 0 Dec 30 11:42 test -rw------- 1 ether staff 0 Dec 30 11:43 test2 -rw------- 1 ether staff 0 Dec 30 11:43 test3 The test2 file is created with an old mtime, and the atime is set to now (as it is a new file), which is correct. However, test3 is created with an old atime, but is not set properly on the file. To be sure this is not just behaviour seen with new files, let's modify an old file: : [ether@tequila ~]$; touch -a -t 200801010000 test : [ether@tequila ~]$; ls -l test -rw------- 1 ether staff 0 Dec 30 11:42 test : [ether@tequila ~]$; ls -lu test -rw------- 1 ether staff 0 Dec 30 11:45 test So it would seem that atimes cannot be set explicitly (it is always reset to "now" when either mtime or atime modifications are submitted). Is this something inherent to the filesystem itself, is it something that can be changed, or am I totally crazy and looking in the wrong place? PS. the output of mount is: : [ether@tequila ~]$; mount /dev/disk0s2 on / (hfs, local, journaled) devfs on /dev (devfs, local, nobrowse) map -hosts on /net (autofs, nosuid, automounted, nobrowse) map auto_home on /home (autofs, automounted, nobrowse) ...and Disk Utility says that the drive is of type "Mac OS Extended (Journaled)".

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  • load-causing processes disappearing from "top" ps -o pcpu shows bogus numbers

    - by Alec Matusis
    I administer a large number of servers, and I have this problem only with Ubuntu 10.04 LTS: I run a server under normal load (say load average 3.0 on an 8-core server). The "top" command shows processes taking certain % of CPU that cause this load average: say PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 11008 mysql 20 0 25.9g 22g 5496 S 67 76.0 643539:38 mysqld ps -o pcpu,pid -p11008 %CPU PID 53.1 11008 , everything is consistent. The all of the sudden, the process causing the load average disappears from "top", but the process continues to run normally (albeit with a slight performance decrease), and the system load average becomes somewhat higher. The output of ps -o pcpu becomes bogus: # ps -o pcpu,pid -p11008 %CPU PID 317910278 1587 This happened to at least 5 different severs (different brand new IBM System X hardware), each running different software: one httpd 2.2, one mysqld 5.1, and one Twisted Python TCP servers. Each time the kernel was between 2.6.32-32-server and 2.6.32-40-server. I updated some machines to 2.6.32-41-server, and it has not happened on those yet, but the bug is rare (once every 60 days or so). This is from an affected machine: top - 10:39:06 up 73 days, 17:57, 3 users, load average: 6.62, 5.60, 5.34 Tasks: 207 total, 2 running, 205 sleeping, 0 stopped, 0 zombie Cpu(s): 11.4%us, 18.0%sy, 0.0%ni, 66.3%id, 4.3%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 74341464k total, 71985004k used, 2356460k free, 236456k buffers Swap: 3906552k total, 328k used, 3906224k free, 24838212k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 805 root 20 0 0 0 0 S 3 0.0 1493:09 fct0-worker 982 root 20 0 0 0 0 S 1 0.0 111:35.05 fioa-data-groom 914 root 20 0 0 0 0 S 0 0.0 884:42.71 fct1-worker 1068 root 20 0 19364 1496 1060 R 0 0.0 0:00.02 top Nothing causing high load is showing on top, but I have two highly loaded mysqld instances on it, that suddenly show crazy %CPU: #ps -o pcpu,pid,cmd -p1587 %CPU PID CMD 317713124 1587 /nail/encap/mysql-5.1.60/libexec/mysqld and #ps -o pcpu,pid,cmd -p1624 %CPU PID CMD 2802 1624 /nail/encap/mysql-5.1.60/libexec/mysqld Here are the numbers from # cat /proc/1587/stat 1587 (mysqld) S 1212 1088 1088 0 -1 4202752 14307313 0 162 0 85773299069 4611685932654088833 0 0 20 0 52 0 3549 27255418880 5483524 18446744073709551615 4194304 11111617 140733749236976 140733749235984 8858659 0 552967 4102 26345 18446744073709551615 0 0 17 5 0 0 0 0 0 the 14th and 15th numbers according to man proc are supposed to be utime %lu Amount of time that this process has been scheduled in user mode, measured in clock ticks (divide by sysconf(_SC_CLK_TCK). This includes guest time, guest_time (time spent running a virtual CPU, see below), so that applications that are not aware of the guest time field do not lose that time from their calculations. stime %lu Amount of time that this process has been scheduled in kernel mode, measured in clock ticks (divide by sysconf(_SC_CLK_TCK). On a normal server, these numbers are advancing, every time I check the /proc/PID/stat. On a buggy server, these numbers are stuck at a ridiculously high value like 4611685932654088833, and it's not changing. Has anyone encountered this bug?

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  • A Taxonomy of Numerical Methods v1

    - by JoshReuben
    Numerical Analysis – When, What, (but not how) Once you understand the Math & know C++, Numerical Methods are basically blocks of iterative & conditional math code. I found the real trick was seeing the forest for the trees – knowing which method to use for which situation. Its pretty easy to get lost in the details – so I’ve tried to organize these methods in a way that I can quickly look this up. I’ve included links to detailed explanations and to C++ code examples. I’ve tried to classify Numerical methods in the following broad categories: Solving Systems of Linear Equations Solving Non-Linear Equations Iteratively Interpolation Curve Fitting Optimization Numerical Differentiation & Integration Solving ODEs Boundary Problems Solving EigenValue problems Enjoy – I did ! Solving Systems of Linear Equations Overview Solve sets of algebraic equations with x unknowns The set is commonly in matrix form Gauss-Jordan Elimination http://en.wikipedia.org/wiki/Gauss%E2%80%93Jordan_elimination C++: http://www.codekeep.net/snippets/623f1923-e03c-4636-8c92-c9dc7aa0d3c0.aspx Produces solution of the equations & the coefficient matrix Efficient, stable 2 steps: · Forward Elimination – matrix decomposition: reduce set to triangular form (0s below the diagonal) or row echelon form. If degenerate, then there is no solution · Backward Elimination –write the original matrix as the product of ints inverse matrix & its reduced row-echelon matrix à reduce set to row canonical form & use back-substitution to find the solution to the set Elementary ops for matrix decomposition: · Row multiplication · Row switching · Add multiples of rows to other rows Use pivoting to ensure rows are ordered for achieving triangular form LU Decomposition http://en.wikipedia.org/wiki/LU_decomposition C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-lu-decomposition-for-solving.html Represent the matrix as a product of lower & upper triangular matrices A modified version of GJ Elimination Advantage – can easily apply forward & backward elimination to solve triangular matrices Techniques: · Doolittle Method – sets the L matrix diagonal to unity · Crout Method - sets the U matrix diagonal to unity Note: both the L & U matrices share the same unity diagonal & can be stored compactly in the same matrix Gauss-Seidel Iteration http://en.wikipedia.org/wiki/Gauss%E2%80%93Seidel_method C++: http://www.nr.com/forum/showthread.php?t=722 Transform the linear set of equations into a single equation & then use numerical integration (as integration formulas have Sums, it is implemented iteratively). an optimization of Gauss-Jacobi: 1.5 times faster, requires 0.25 iterations to achieve the same tolerance Solving Non-Linear Equations Iteratively find roots of polynomials – there may be 0, 1 or n solutions for an n order polynomial use iterative techniques Iterative methods · used when there are no known analytical techniques · Requires set functions to be continuous & differentiable · Requires an initial seed value – choice is critical to convergence à conduct multiple runs with different starting points & then select best result · Systematic - iterate until diminishing returns, tolerance or max iteration conditions are met · bracketing techniques will always yield convergent solutions, non-bracketing methods may fail to converge Incremental method if a nonlinear function has opposite signs at 2 ends of a small interval x1 & x2, then there is likely to be a solution in their interval – solutions are detected by evaluating a function over interval steps, for a change in sign, adjusting the step size dynamically. Limitations – can miss closely spaced solutions in large intervals, cannot detect degenerate (coinciding) solutions, limited to functions that cross the x-axis, gives false positives for singularities Fixed point method http://en.wikipedia.org/wiki/Fixed-point_iteration C++: http://books.google.co.il/books?id=weYj75E_t6MC&pg=PA79&lpg=PA79&dq=fixed+point+method++c%2B%2B&source=bl&ots=LQ-5P_taoC&sig=lENUUIYBK53tZtTwNfHLy5PEWDk&hl=en&sa=X&ei=wezDUPW1J5DptQaMsIHQCw&redir_esc=y#v=onepage&q=fixed%20point%20method%20%20c%2B%2B&f=false Algebraically rearrange a solution to isolate a variable then apply incremental method Bisection method http://en.wikipedia.org/wiki/Bisection_method C++: http://numericalcomputing.wordpress.com/category/algorithms/ Bracketed - Select an initial interval, keep bisecting it ad midpoint into sub-intervals and then apply incremental method on smaller & smaller intervals – zoom in Adv: unaffected by function gradient à reliable Disadv: slow convergence False Position Method http://en.wikipedia.org/wiki/False_position_method C++: http://www.dreamincode.net/forums/topic/126100-bisection-and-false-position-methods/ Bracketed - Select an initial interval , & use the relative value of function at interval end points to select next sub-intervals (estimate how far between the end points the solution might be & subdivide based on this) Newton-Raphson method http://en.wikipedia.org/wiki/Newton's_method C++: http://www-users.cselabs.umn.edu/classes/Summer-2012/csci1113/index.php?page=./newt3 Also known as Newton's method Convenient, efficient Not bracketed – only a single initial guess is required to start iteration – requires an analytical expression for the first derivative of the function as input. Evaluates the function & its derivative at each step. Can be extended to the Newton MutiRoot method for solving multiple roots Can be easily applied to an of n-coupled set of non-linear equations – conduct a Taylor Series expansion of a function, dropping terms of order n, rewrite as a Jacobian matrix of PDs & convert to simultaneous linear equations !!! Secant Method http://en.wikipedia.org/wiki/Secant_method C++: http://forum.vcoderz.com/showthread.php?p=205230 Unlike N-R, can estimate first derivative from an initial interval (does not require root to be bracketed) instead of inputting it Since derivative is approximated, may converge slower. Is fast in practice as it does not have to evaluate the derivative at each step. Similar implementation to False Positive method Birge-Vieta Method http://mat.iitm.ac.in/home/sryedida/public_html/caimna/transcendental/polynomial%20methods/bv%20method.html C++: http://books.google.co.il/books?id=cL1boM2uyQwC&pg=SA3-PA51&lpg=SA3-PA51&dq=Birge-Vieta+Method+c%2B%2B&source=bl&ots=QZmnDTK3rC&sig=BPNcHHbpR_DKVoZXrLi4nVXD-gg&hl=en&sa=X&ei=R-_DUK2iNIjzsgbE5ID4Dg&redir_esc=y#v=onepage&q=Birge-Vieta%20Method%20c%2B%2B&f=false combines Horner's method of polynomial evaluation (transforming into lesser degree polynomials that are more computationally efficient to process) with Newton-Raphson to provide a computational speed-up Interpolation Overview Construct new data points for as close as possible fit within range of a discrete set of known points (that were obtained via sampling, experimentation) Use Taylor Series Expansion of a function f(x) around a specific value for x Linear Interpolation http://en.wikipedia.org/wiki/Linear_interpolation C++: http://www.hamaluik.com/?p=289 Straight line between 2 points à concatenate interpolants between each pair of data points Bilinear Interpolation http://en.wikipedia.org/wiki/Bilinear_interpolation C++: http://supercomputingblog.com/graphics/coding-bilinear-interpolation/2/ Extension of the linear function for interpolating functions of 2 variables – perform linear interpolation first in 1 direction, then in another. Used in image processing – e.g. texture mapping filter. Uses 4 vertices to interpolate a value within a unit cell. Lagrange Interpolation http://en.wikipedia.org/wiki/Lagrange_polynomial C++: http://www.codecogs.com/code/maths/approximation/interpolation/lagrange.php For polynomials Requires recomputation for all terms for each distinct x value – can only be applied for small number of nodes Numerically unstable Barycentric Interpolation http://epubs.siam.org/doi/pdf/10.1137/S0036144502417715 C++: http://www.gamedev.net/topic/621445-barycentric-coordinates-c-code-check/ Rearrange the terms in the equation of the Legrange interpolation by defining weight functions that are independent of the interpolated value of x Newton Divided Difference Interpolation http://en.wikipedia.org/wiki/Newton_polynomial C++: http://jee-appy.blogspot.co.il/2011/12/newton-divided-difference-interpolation.html Hermite Divided Differences: Interpolation polynomial approximation for a given set of data points in the NR form - divided differences are used to approximately calculate the various differences. For a given set of 3 data points , fit a quadratic interpolant through the data Bracketed functions allow Newton divided differences to be calculated recursively Difference table Cubic Spline Interpolation http://en.wikipedia.org/wiki/Spline_interpolation C++: https://www.marcusbannerman.co.uk/index.php/home/latestarticles/42-articles/96-cubic-spline-class.html Spline is a piecewise polynomial Provides smoothness – for interpolations with significantly varying data Use weighted coefficients to bend the function to be smooth & its 1st & 2nd derivatives are continuous through the edge points in the interval Curve Fitting A generalization of interpolating whereby given data points may contain noise à the curve does not necessarily pass through all the points Least Squares Fit http://en.wikipedia.org/wiki/Least_squares C++: http://www.ccas.ru/mmes/educat/lab04k/02/least-squares.c Residual – difference between observed value & expected value Model function is often chosen as a linear combination of the specified functions Determines: A) The model instance in which the sum of squared residuals has the least value B) param values for which model best fits data Straight Line Fit Linear correlation between independent variable and dependent variable Linear Regression http://en.wikipedia.org/wiki/Linear_regression C++: http://www.oocities.org/david_swaim/cpp/linregc.htm Special case of statistically exact extrapolation Leverage least squares Given a basis function, the sum of the residuals is determined and the corresponding gradient equation is expressed as a set of normal linear equations in matrix form that can be solved (e.g. using LU Decomposition) Can be weighted - Drop the assumption that all errors have the same significance –-> confidence of accuracy is different for each data point. Fit the function closer to points with higher weights Polynomial Fit - use a polynomial basis function Moving Average http://en.wikipedia.org/wiki/Moving_average C++: http://www.codeproject.com/Articles/17860/A-Simple-Moving-Average-Algorithm Used for smoothing (cancel fluctuations to highlight longer-term trends & cycles), time series data analysis, signal processing filters Replace each data point with average of neighbors. Can be simple (SMA), weighted (WMA), exponential (EMA). Lags behind latest data points – extra weight can be given to more recent data points. Weights can decrease arithmetically or exponentially according to distance from point. Parameters: smoothing factor, period, weight basis Optimization Overview Given function with multiple variables, find Min (or max by minimizing –f(x)) Iterative approach Efficient, but not necessarily reliable Conditions: noisy data, constraints, non-linear models Detection via sign of first derivative - Derivative of saddle points will be 0 Local minima Bisection method Similar method for finding a root for a non-linear equation Start with an interval that contains a minimum Golden Search method http://en.wikipedia.org/wiki/Golden_section_search C++: http://www.codecogs.com/code/maths/optimization/golden.php Bisect intervals according to golden ratio 0.618.. Achieves reduction by evaluating a single function instead of 2 Newton-Raphson Method Brent method http://en.wikipedia.org/wiki/Brent's_method C++: http://people.sc.fsu.edu/~jburkardt/cpp_src/brent/brent.cpp Based on quadratic or parabolic interpolation – if the function is smooth & parabolic near to the minimum, then a parabola fitted through any 3 points should approximate the minima – fails when the 3 points are collinear , in which case the denominator is 0 Simplex Method http://en.wikipedia.org/wiki/Simplex_algorithm C++: http://www.codeguru.com/cpp/article.php/c17505/Simplex-Optimization-Algorithm-and-Implemetation-in-C-Programming.htm Find the global minima of any multi-variable function Direct search – no derivatives required At each step it maintains a non-degenerative simplex – a convex hull of n+1 vertices. Obtains the minimum for a function with n variables by evaluating the function at n-1 points, iteratively replacing the point of worst result with the point of best result, shrinking the multidimensional simplex around the best point. Point replacement involves expanding & contracting the simplex near the worst value point to determine a better replacement point Oscillation can be avoided by choosing the 2nd worst result Restart if it gets stuck Parameters: contraction & expansion factors Simulated Annealing http://en.wikipedia.org/wiki/Simulated_annealing C++: http://code.google.com/p/cppsimulatedannealing/ Analogy to heating & cooling metal to strengthen its structure Stochastic method – apply random permutation search for global minima - Avoid entrapment in local minima via hill climbing Heating schedule - Annealing schedule params: temperature, iterations at each temp, temperature delta Cooling schedule – can be linear, step-wise or exponential Differential Evolution http://en.wikipedia.org/wiki/Differential_evolution C++: http://www.amichel.com/de/doc/html/ More advanced stochastic methods analogous to biological processes: Genetic algorithms, evolution strategies Parallel direct search method against multiple discrete or continuous variables Initial population of variable vectors chosen randomly – if weighted difference vector of 2 vectors yields a lower objective function value then it replaces the comparison vector Many params: #parents, #variables, step size, crossover constant etc Convergence is slow – many more function evaluations than simulated annealing Numerical Differentiation Overview 2 approaches to finite difference methods: · A) approximate function via polynomial interpolation then differentiate · B) Taylor series approximation – additionally provides error estimate Finite Difference methods http://en.wikipedia.org/wiki/Finite_difference_method C++: http://www.wpi.edu/Pubs/ETD/Available/etd-051807-164436/unrestricted/EAMPADU.pdf Find differences between high order derivative values - Approximate differential equations by finite differences at evenly spaced data points Based on forward & backward Taylor series expansion of f(x) about x plus or minus multiples of delta h. Forward / backward difference - the sums of the series contains even derivatives and the difference of the series contains odd derivatives – coupled equations that can be solved. Provide an approximation of the derivative within a O(h^2) accuracy There is also central difference & extended central difference which has a O(h^4) accuracy Richardson Extrapolation http://en.wikipedia.org/wiki/Richardson_extrapolation C++: http://mathscoding.blogspot.co.il/2012/02/introduction-richardson-extrapolation.html A sequence acceleration method applied to finite differences Fast convergence, high accuracy O(h^4) Derivatives via Interpolation Cannot apply Finite Difference method to discrete data points at uneven intervals – so need to approximate the derivative of f(x) using the derivative of the interpolant via 3 point Lagrange Interpolation Note: the higher the order of the derivative, the lower the approximation precision Numerical Integration Estimate finite & infinite integrals of functions More accurate procedure than numerical differentiation Use when it is not possible to obtain an integral of a function analytically or when the function is not given, only the data points are Newton Cotes Methods http://en.wikipedia.org/wiki/Newton%E2%80%93Cotes_formulas C++: http://www.siafoo.net/snippet/324 For equally spaced data points Computationally easy – based on local interpolation of n rectangular strip areas that is piecewise fitted to a polynomial to get the sum total area Evaluate the integrand at n+1 evenly spaced points – approximate definite integral by Sum Weights are derived from Lagrange Basis polynomials Leverage Trapezoidal Rule for default 2nd formulas, Simpson 1/3 Rule for substituting 3 point formulas, Simpson 3/8 Rule for 4 point formulas. For 4 point formulas use Bodes Rule. Higher orders obtain more accurate results Trapezoidal Rule uses simple area, Simpsons Rule replaces the integrand f(x) with a quadratic polynomial p(x) that uses the same values as f(x) for its end points, but adds a midpoint Romberg Integration http://en.wikipedia.org/wiki/Romberg's_method C++: http://code.google.com/p/romberg-integration/downloads/detail?name=romberg.cpp&can=2&q= Combines trapezoidal rule with Richardson Extrapolation Evaluates the integrand at equally spaced points The integrand must have continuous derivatives Each R(n,m) extrapolation uses a higher order integrand polynomial replacement rule (zeroth starts with trapezoidal) à a lower triangular matrix set of equation coefficients where the bottom right term has the most accurate approximation. The process continues until the difference between 2 successive diagonal terms becomes sufficiently small. Gaussian Quadrature http://en.wikipedia.org/wiki/Gaussian_quadrature C++: http://www.alglib.net/integration/gaussianquadratures.php Data points are chosen to yield best possible accuracy – requires fewer evaluations Ability to handle singularities, functions that are difficult to evaluate The integrand can include a weighting function determined by a set of orthogonal polynomials. Points & weights are selected so that the integrand yields the exact integral if f(x) is a polynomial of degree <= 2n+1 Techniques (basically different weighting functions): · Gauss-Legendre Integration w(x)=1 · Gauss-Laguerre Integration w(x)=e^-x · Gauss-Hermite Integration w(x)=e^-x^2 · Gauss-Chebyshev Integration w(x)= 1 / Sqrt(1-x^2) Solving ODEs Use when high order differential equations cannot be solved analytically Evaluated under boundary conditions RK for systems – a high order differential equation can always be transformed into a coupled first order system of equations Euler method http://en.wikipedia.org/wiki/Euler_method C++: http://rosettacode.org/wiki/Euler_method First order Runge–Kutta method. Simple recursive method – given an initial value, calculate derivative deltas. Unstable & not very accurate (O(h) error) – not used in practice A first-order method - the local error (truncation error per step) is proportional to the square of the step size, and the global error (error at a given time) is proportional to the step size In evolving solution between data points xn & xn+1, only evaluates derivatives at beginning of interval xn à asymmetric at boundaries Higher order Runge Kutta http://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods C++: http://www.dreamincode.net/code/snippet1441.htm 2nd & 4th order RK - Introduces parameterized midpoints for more symmetric solutions à accuracy at higher computational cost Adaptive RK – RK-Fehlberg – estimate the truncation at each integration step & automatically adjust the step size to keep error within prescribed limits. At each step 2 approximations are compared – if in disagreement to a specific accuracy, the step size is reduced Boundary Value Problems Where solution of differential equations are located at 2 different values of the independent variable x à more difficult, because cannot just start at point of initial value – there may not be enough starting conditions available at the end points to produce a unique solution An n-order equation will require n boundary conditions – need to determine the missing n-1 conditions which cause the given conditions at the other boundary to be satisfied Shooting Method http://en.wikipedia.org/wiki/Shooting_method C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-shooting-method-for-solving.html Iteratively guess the missing values for one end & integrate, then inspect the discrepancy with the boundary values of the other end to adjust the estimate Given the starting boundary values u1 & u2 which contain the root u, solve u given the false position method (solving the differential equation as an initial value problem via 4th order RK), then use u to solve the differential equations. Finite Difference Method For linear & non-linear systems Higher order derivatives require more computational steps – some combinations for boundary conditions may not work though Improve the accuracy by increasing the number of mesh points Solving EigenValue Problems An eigenvalue can substitute a matrix when doing matrix multiplication à convert matrix multiplication into a polynomial EigenValue For a given set of equations in matrix form, determine what are the solution eigenvalue & eigenvectors Similar Matrices - have same eigenvalues. Use orthogonal similarity transforms to reduce a matrix to diagonal form from which eigenvalue(s) & eigenvectors can be computed iteratively Jacobi method http://en.wikipedia.org/wiki/Jacobi_method C++: http://people.sc.fsu.edu/~jburkardt/classes/acs2_2008/openmp/jacobi/jacobi.html Robust but Computationally intense – use for small matrices < 10x10 Power Iteration http://en.wikipedia.org/wiki/Power_iteration For any given real symmetric matrix, generate the largest single eigenvalue & its eigenvectors Simplest method – does not compute matrix decomposition à suitable for large, sparse matrices Inverse Iteration Variation of power iteration method – generates the smallest eigenvalue from the inverse matrix Rayleigh Method http://en.wikipedia.org/wiki/Rayleigh's_method_of_dimensional_analysis Variation of power iteration method Rayleigh Quotient Method Variation of inverse iteration method Matrix Tri-diagonalization Method Use householder algorithm to reduce an NxN symmetric matrix to a tridiagonal real symmetric matrix vua N-2 orthogonal transforms     Whats Next Outside of Numerical Methods there are lots of different types of algorithms that I’ve learned over the decades: Data Mining – (I covered this briefly in a previous post: http://geekswithblogs.net/JoshReuben/archive/2007/12/31/ssas-dm-algorithms.aspx ) Search & Sort Routing Problem Solving Logical Theorem Proving Planning Probabilistic Reasoning Machine Learning Solvers (eg MIP) Bioinformatics (Sequence Alignment, Protein Folding) Quant Finance (I read Wilmott’s books – interesting) Sooner or later, I’ll cover the above topics as well.

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  • NET Math Libraries

    - by JoshReuben
    NET Mathematical Libraries   .NET Builder for Matlab The MathWorks Inc. - http://www.mathworks.com/products/netbuilder/ MATLAB Builder NE generates MATLAB based .NET and COM components royalty-free deployment creates the components by encrypting MATLAB functions and generating either a .NET or COM wrapper around them. .NET/Link for Mathematica www.wolfram.com a product that 2-way integrates Mathematica and Microsoft's .NET platform call .NET from Mathematica - use arbitrary .NET types directly from the Mathematica language. use and control the Mathematica kernel from a .NET program. turns Mathematica into a scripting shell to leverage the computational services of Mathematica. write custom front ends for Mathematica or use Mathematica as a computational engine for another program comes with full source code. Leverages MathLink - a Wolfram Research's protocol for sending data and commands back and forth between Mathematica and other programs. .NET/Link abstracts the low-level details of the MathLink C API. Extreme Optimization http://www.extremeoptimization.com/ a collection of general-purpose mathematical and statistical classes built for the.NET framework. It combines a math library, a vector and matrix library, and a statistics library in one package. download the trial of version 4.0 to try it out. Multi-core ready - Full support for Task Parallel Library features including cancellation. Broad base of algorithms covering a wide range of numerical techniques, including: linear algebra (BLAS and LAPACK routines), numerical analysis (integration and differentiation), equation solvers. Mathematics leverages parallelism using .NET 4.0's Task Parallel Library. Basic math: Complex numbers, 'special functions' like Gamma and Bessel functions, numerical differentiation. Solving equations: Solve equations in one variable, or solve systems of linear or nonlinear equations. Curve fitting: Linear and nonlinear curve fitting, cubic splines, polynomials, orthogonal polynomials. Optimization: find the minimum or maximum of a function in one or more variables, linear programming and mixed integer programming. Numerical integration: Compute integrals over finite or infinite intervals, over 2D and higher dimensional regions. Integrate systems of ordinary differential equations (ODE's). Fast Fourier Transforms: 1D and 2D FFT's using managed or fast native code (32 and 64 bit) BigInteger, BigRational, and BigFloat: Perform operations with arbitrary precision. Vector and Matrix Library Real and complex vectors and matrices. Single and double precision for elements. Structured matrix types: including triangular, symmetrical and band matrices. Sparse matrices. Matrix factorizations: LU decomposition, QR decomposition, singular value decomposition, Cholesky decomposition, eigenvalue decomposition. Portability and performance: Calculations can be done in 100% managed code, or in hand-optimized processor-specific native code (32 and 64 bit). Statistics Data manipulation: Sort and filter data, process missing values, remove outliers, etc. Supports .NET data binding. Statistical Models: Simple, multiple, nonlinear, logistic, Poisson regression. Generalized Linear Models. One and two-way ANOVA. Hypothesis Tests: 12 14 hypothesis tests, including the z-test, t-test, F-test, runs test, and more advanced tests, such as the Anderson-Darling test for normality, one and two-sample Kolmogorov-Smirnov test, and Levene's test for homogeneity of variances. Multivariate Statistics: K-means cluster analysis, hierarchical cluster analysis, principal component analysis (PCA), multivariate probability distributions. Statistical Distributions: 25 29 continuous and discrete statistical distributions, including uniform, Poisson, normal, lognormal, Weibull and Gumbel (extreme value) distributions. Random numbers: Random variates from any distribution, 4 high-quality random number generators, low discrepancy sequences, shufflers. New in version 4.0 (November, 2010) Support for .NET Framework Version 4.0 and Visual Studio 2010 TPL Parallellized – multicore ready sparse linear program solver - can solve problems with more than 1 million variables. Mixed integer linear programming using a branch and bound algorithm. special functions: hypergeometric, Riemann zeta, elliptic integrals, Frensel functions, Dawson's integral. Full set of window functions for FFT's. Product  Price Update subscription Single Developer License $999  $399  Team License (3 developers) $1999  $799  Department License (8 developers) $3999  $1599  Site License (Unlimited developers in one physical location) $7999  $3199    NMath http://www.centerspace.net .NET math and statistics libraries matrix and vector classes random number generators Fast Fourier Transforms (FFTs) numerical integration linear programming linear regression curve and surface fitting optimization hypothesis tests analysis of variance (ANOVA) probability distributions principal component analysis cluster analysis built on the Intel Math Kernel Library (MKL), which contains highly-optimized, extensively-threaded versions of BLAS (Basic Linear Algebra Subroutines) and LAPACK (Linear Algebra PACKage). Product  Price Update subscription Single Developer License $1295 $388 Team License (5 developers) $5180 $1554   DotNumerics http://www.dotnumerics.com/NumericalLibraries/Default.aspx free DotNumerics is a website dedicated to numerical computing for .NET that includes a C# Numerical Library for .NET containing algorithms for Linear Algebra, Differential Equations and Optimization problems. The Linear Algebra library includes CSLapack, CSBlas and CSEispack, ports from Fortran to C# of LAPACK, BLAS and EISPACK, respectively. Linear Algebra (CSLapack, CSBlas and CSEispack). Systems of linear equations, eigenvalue problems, least-squares solutions of linear systems and singular value problems. Differential Equations. Initial-value problem for nonstiff and stiff ordinary differential equations ODEs (explicit Runge-Kutta, implicit Runge-Kutta, Gear's BDF and Adams-Moulton). Optimization. Unconstrained and bounded constrained optimization of multivariate functions (L-BFGS-B, Truncated Newton and Simplex methods).   Math.NET Numerics http://numerics.mathdotnet.com/ free an open source numerical library - includes special functions, linear algebra, probability models, random numbers, interpolation, integral transforms. A merger of dnAnalytics with Math.NET Iridium in addition to a purely managed implementation will also support native hardware optimization. constants & special functions complex type support real and complex, dense and sparse linear algebra (with LU, QR, eigenvalues, ... decompositions) non-uniform probability distributions, multivariate distributions, sample generation alternative uniform random number generators descriptive statistics, including order statistics various interpolation methods, including barycentric approaches and splines numerical function integration (quadrature) routines integral transforms, like fourier transform (FFT) with arbitrary lengths support, and hartley spectral-space aware sequence manipulation (signal processing) combinatorics, polynomials, quaternions, basic number theory. parallelized where appropriate, to leverage multi-core and multi-processor systems fully managed or (if available) using native libraries (Intel MKL, ACMS, CUDA, FFTW) provides a native facade for F# developers

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  • Chainload boot of Ubuntu installed on 32GB SD card from legacy Grub boot on USB

    - by Gary Darsey
    I have Ubuntu installed on a 32 GB SD card (in the Storage Expansion slot on an Acer Aspire One) with Grub2 installed in the same partition. I boot into legacy Grub on a USB drive and would like to boot by chainloading Grub2 from Grub (kernel/initrd or symlink booting would also be fine), but I haven't figured out how to do this from legacy Grub CLI. Output from blkid for this partition is /dev/mmcblk0p1: LABEL="Ubuntu" UUID="7ceb9fa7-238c-4c5d-bb8e-2c655652ddec" TYPE='ext4" / fdisk -lu information Boot indicator ID 83. Related entries in grub.cfg: search --no-floppy --fs-uuid --set-root 7ceb9fa7-238c-4c5d-bb8e-2c655652ddec linux /boot/vmlinuz-3.5.0-17-generic root=UUID=7ceb9fa7-238c-4c5d-bb8e-2c655652ddec... initrd /boot/initrd.img-3.5.0-17-generic I can't seem to replicate this in legacy Grub. Is there any way get Grub2 to chainload? How do I set root with UUID in legacy Grub? I prefer to boot from USB. Would Grub2 on USB (copying the grub.cfg generated during installation) be an option?

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  • Principes universels du design de William Lidwell , Kritina Holden , Jill Butler, critique par Benwit

    Je viens de lire un livre intitulé "Principes universels du design" [IMG]http://images-eu.amazon.com/images/P/2212128622.08.LZZZZZZZ.jpg[/IMG] Sur la couverture recto/verso, ce qui ressemble à des traits jaunes verticaux, ce sont les noms des 125 principes de design présentés dans ce livre. Entendons nous bien, il ne s'agit pas de Design Pattern (modèle de conception pour votre modèle de données) mais des principes de design utilisé lors de la conception d'objets (IHM comprise). Quels principes de design utilisez vous dans la conception de vos IHM ? Avez vous lu ce livre, pensez vous le lire ?...

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  • Développement d'applications professionnelles avec Android 2 de Reto Meier, critique par verdvaine yan

    Je viens de lire "Développement d'applications professionnelles avec Android 2" de Reto Meier, ingénieur chez Google. [IMG]http://images-eu.amazon.com/images/P/274402452X.08.LZZZZZZZ.jpg[/IMG] Je le trouve très complémentaire aux tutoriaux qu'on trouve sur Internet. Il aborde beaucoup de sujets et le nombre de pages n'est pas dù à des captures d'écrans ! Ce que j'ai particulièremen apprécié, ce sont toutes les petites informations tirées de son expérience qu'il distille au fil des pages. L'avez vous lu ? Si oui, par rapport à d'autres livres sur le sujet ? Allez vous le lire ?...

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  • How to mount a hidden NTFS WinRE which are on an external HDD

    - by annabinna
    A friend have given me her external hard drive which contains a backup of his Windows data. The disk has two NTFS partitions, once of them tagged as WinRe. When I do fdisk -lu I get Disk /dev/sdc: 120.0 GB, 120034123776 bytes 255 heads, 63 sectors/track, 14593 cylinders, total 234441648 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x59725972 Dispositiu Arrenc. Inici Final Blocs Id Sistema /dev/sdc1 2048 3074047 1536000 27 Hidden NTFS WinRE /dev/sdc2 * 3074048 234438655 115682304 7 HPFS/NTFS/exFAT I never fought against this type of partitions and I haven't any idea of how to mount this and recover the data. Can someone help me?

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  • Développement d'applications professionnelles avec Android 2 de Reto Meier, critique par Benwit

    Je viens de lire "Développement d'applications professionnelles avec Android 2" de Reto Meier, ingénieur chez Google. [IMG]http://images-eu.amazon.com/images/P/274402452X.08.LZZZZZZZ.jpg[/IMG] Je le trouve très complémentaire aux tutoriaux qu'on trouve sur Internet. Il aborde beaucoup de sujets et le nombre de pages n'est pas dù à des captures d'écrans ! Ce que j'ai particulièremen apprécié, ce sont toutes les petites informations tirées de son expérience qu'il distille au fil des pages. L'avez vous lu ? Si oui, par rapport à d'autres livres sur le sujet ? Allez vous le lire ?...

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  • Justice : Apple s'attaque à Android 4.1 dans un deuxième procès contre Samsung

    Justice : Apple s'attaque directement à Android 4.1 Dans un deuxième procès qui l'oppose à Samsung Combien de fois avons-nous lu, dans certains commentaires de nos articles qui traitent des procès qu'Apple intente aux constructeurs qui lancent des modèles sous Android, que Google et son OS mobile n'étaient pas visés ? Nous avions beau expliquer que c'était bien Android qui était dans la ligne de mire d'Apple (ce qui est d'ailleurs l'analyse de Google), pour certains, nous ne faisions qu'extrapoler pour jeter le doute dans l'esprit des développeurs de cette plateforme. Que ceux-là veuillent bien nous excuser. Apple assigne aujourd'hui Android 4.1 en justice. ...

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  • Bing disponible comme plateforme pour développeurs avec l'imagerie 3D et la recherche vocale contextuelle

    Bing disponible comme plateforme pour développeurs avec l'imagerie 3D et la recherche vocale contextuelleMicrosoft a annoncé pendant la Build 2013 à Seattle qu'il a ouvert son outil de recherche Bing comme plateforme pour développeurs. Gurdeep Singh Pall, Vice-Président de l'entreprise, a fait une démonstration pour exposer les capacités dont les développeurs pourront désormais bénéficier. Pall a montré comment ajouter un élément à la to-do liste d'une application tiers en faisant usage du contrôle vocal de Bing. Dans le cas d'espèce, il a créé un mémento sur ses intentions de voyage en direction de l'Espagne.La démonstration est allée un peu plus loin. Pall a obtenu des informations lu...

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  • LINQ Except operator and object equality

    - by Abhijeet Patel
    Here is an interesting issue I noticed when using the Except Operator: I have list of users from which I want to exclude some users: The list of users is coming from an XML file: The code goes like this: interface IUser { int ID { get; set; } string Name { get; set; } } class User: IUser { #region IUser Members public int ID { get; set; } public string Name { get; set; } #endregion public override string ToString() { return ID + ":" +Name; } public static IEnumerable<IUser> GetMatchingUsers(IEnumerable<IUser> users) { IEnumerable<IUser> localList = new List<User> { new User{ ID=4, Name="James"}, new User{ ID=5, Name="Tom"} }.OfType<IUser>(); var matches = from u in users join lu in localList on u.ID equals lu.ID select u; return matches; } } class Program { static void Main(string[] args) { XDocument doc = XDocument.Load("Users.xml"); IEnumerable<IUser> users = doc.Element("Users").Elements("User").Select (u => new User { ID = (int)u.Attribute("id"), Name = (string)u.Attribute("name") } ).OfType<IUser>(); //still a query, objects have not been materialized var matches = User.GetMatchingUsers(users); var excludes = users.Except(matches); // excludes should contain 6 users but here it contains 8 users } } When I call User.GetMatchingUsers(users) I get 2 matches as expected. The issue is that when I call users.Except(matches) The matching users are not being excluded at all! I am expecting 6 users ut "excludes" contains all 8 users instead. Since all I'm doing in GetMatchingUsers(IEnumerable users) is taking the IEnumerable and just returning the IUsers whose ID's match( 2 IUsers in this case), my understanding is that by default "Except" will use reference equality for comparing the objects to be excluded. Is this not how "Except" behaves? What is even more interesting is that if I materialize the objects using .ToList() and then get the matching users, and call "Except", everything works as expected! Like so: IEnumerable users = doc.Element("Users").Elements("User").Select (u = new User { ID = (int)u.Attribute("id"), Name = (string)u.Attribute("name") } ).OfType().ToList(); //explicity materializing all objects by calling ToList() var matches = User.GetMatchingUsers(users); var excludes = users.Except(matches); // excludes now contains 6 users as expected I don't see why I should need to materialize objects for calling "Except" given that its defined on IEnumerable? Any suggesstions / insights would be much appreciated.

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  • how can I fix error: hd0 out of disk?

    - by rux
    I am running Ubuntu 12.04 on a netbook - Acer AS 1410. After a download session, I restarted the computer and it said: error: hd0 out of disk. Press any key to continue... I pressed everything, but it's just frozen there. Any idea what's wrong with it and what I can do to fix it? I haven't been able to run my computer at all since it's frozen like that. Help please! I booted the live cd and ran sudo fdisk -lu into terminal, and here's what it gave me: Disk /dev/sda: 60.0 GB, 60022480896 bytes 255 heads, 63 sectors/track, 7297 cylinders, total 117231408 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x9a696263 Device Boot Start End Blocks Id System /dev/sda3 2048 117229567 58613760 5 Extended /dev/sda5 * 71647232 109039615 18696192 83 Linux /dev/sda6 109041664 117229567 4093952 82 Linux swap / Solaris /dev/sda7 4096 71645183 35820544 83 Linux Partition table entries are not in disk order I am somewhat of a beginner in this, so don't know what this means. any ideas? Thanks!

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  • Find non-ascii characters from a UTF-8 string

    - by user10607
    I need to find the non-ASCII characters from a UTF-8 string. my understanding: UTF-8 is a superset of character encoding in which 0-127 are ascii characters. So if in a UTF-8 string , a characters value is Not between 0-127, then it is not a ascii character , right? Please correct me if i'm wrong here. On the above understanding i have written following code in C : Note: I'm using the Ubuntu gcc compiler to run C code utf-string is xvab c long i; char arr[] = "xvab c"; printf("length : %lu \n", sizeof(arr)); for(i=0; i<sizeof(arr); i++){ char ch = arr[i]; if (isascii(ch)) printf("Ascii character %c\n", ch); else printf("Not ascii character %c\n", ch); } Which prints the output like: length : 9 Ascii character x Not ascii character Not ascii character ? Not ascii character ? Ascii character a Ascii character b Ascii character Ascii character c Ascii character To naked eye length of xvab c seems to be 6, but in code it is coming as 9 ? Correct answer for the xvab c is 1 ...i.e it has only 1 non-ascii character , but in above output it is coming as 3 (times Not ascii character). How can i find the non-ascii character from UTF-8 string, correctly. Please guide on the subject.

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  • Removing malware of a particular kind

    - by Cyclone
    I need to remove some malware from my computer. It is a trojan, and very annoying. It blocks access to Google and search sites. The trojan, with its name spelled out on each line cause it seems to block sites when i reference it in a url, is a r t (some text to mess it up) e m (more text i s First off, what is it, what does it do? Second, why can't I access google or yahoo or any other search sites at all? Third, can it be removed via McAffee? It says it quarantined it when I scanned I found a suspicious process "c"s"r"s"s".exe and it will not let me terminate it, and this is what Mcaffee says it is. Why on earth isn't Mcaffee getting rid of it? I even blocked internet access for this program. Thanks so much, I get kinda freaked out with things like this... Here is my entire Hosts file: 127.0.0.1 go.mail.ru 127.0.0.1 nova.rambler.ru 127.0.0.1 google.ad 127.0.0.1 www.google.ad 127.0.0.1 google.ae 127.0.0.1 www.google.ae 127.0.0.1 google.am 127.0.0.1 www.google.am 127.0.0.1 google.com.ar 127.0.0.1 www.google.com.ar 127.0.0.1 google.as 127.0.0.1 www.google.as 127.0.0.1 google.at 127.0.0.1 www.google.at 127.0.0.1 google.com.au 127.0.0.1 www.google.com.au 127.0.0.1 google.az 127.0.0.1 www.google.az 127.0.0.1 google.ba 127.0.0.1 www.google.ba 127.0.0.1 google.be 127.0.0.1 www.google.be 127.0.0.1 google.bg 127.0.0.1 www.google.bg 127.0.0.1 google.bs 127.0.0.1 www.google.bs 127.0.0.1 google.com.by 127.0.0.1 www.google.com.by 127.0.0.1 google.ca 127.0.0.1 www.google.ca 127.0.0.1 google.ch 127.0.0.1 www.google.ch 127.0.0.1 google.cn 127.0.0.1 www.google.cn 127.0.0.1 google.cz 127.0.0.1 www.google.cz 127.0.0.1 google.de 127.0.0.1 www.google.de 127.0.0.1 google.dk 127.0.0.1 www.google.dk 127.0.0.1 google.ee 127.0.0.1 www.google.ee 127.0.0.1 google.es 127.0.0.1 www.google.es 127.0.0.1 google.fi 127.0.0.1 www.google.fi 127.0.0.1 google.fr 127.0.0.1 www.google.fr 127.0.0.1 google.gr 127.0.0.1 www.google.gr 127.0.0.1 google.com.hk 127.0.0.1 www.google.com.hk 127.0.0.1 google.hr 127.0.0.1 www.google.hr 127.0.0.1 google.hu 127.0.0.1 www.google.hu 127.0.0.1 google.ie 127.0.0.1 www.google.ie 127.0.0.1 google.co.il 127.0.0.1 www.google.co.il 127.0.0.1 google.co.in 127.0.0.1 www.google.co.in 127.0.0.1 google.is 127.0.0.1 www.google.is 127.0.0.1 google.it 127.0.0.1 www.google.it 127.0.0.1 google.co.jp 127.0.0.1 www.google.co.jp 127.0.0.1 google.kg 127.0.0.1 www.google.kg 127.0.0.1 google.co.kr 127.0.0.1 www.google.co.kr 127.0.0.1 google.li 127.0.0.1 www.google.li 127.0.0.1 google.lt 127.0.0.1 www.google.lt 127.0.0.1 google.lu 127.0.0.1 www.google.lu 127.0.0.1 google.lv 127.0.0.1 www.google.lv 127.0.0.1 google.md 127.0.0.1 www.google.md 127.0.0.1 google.com.mx 127.0.0.1 www.google.com.mx 127.0.0.1 google.nl 127.0.0.1 www.google.nl 127.0.0.1 google.no 127.0.0.1 www.google.no 127.0.0.1 google.co.nz 127.0.0.1 www.google.co.nz 127.0.0.1 google.com.pe 127.0.0.1 www.google.com.pe 127.0.0.1 google.com.ph 127.0.0.1 www.google.com.ph 127.0.0.1 google.pl 127.0.0.1 www.google.pl 127.0.0.1 google.pt 127.0.0.1 www.google.pt 127.0.0.1 google.ro 127.0.0.1 www.google.ro 127.0.0.1 google.ru 127.0.0.1 www.google.ru 127.0.0.1 google.com.ru 127.0.0.1 www.google.com.ru 127.0.0.1 google.com.sa 127.0.0.1 www.google.com.sa 127.0.0.1 google.se 127.0.0.1 www.google.se 127.0.0.1 google.com.sg 127.0.0.1 www.google.com.sg 127.0.0.1 google.si 127.0.0.1 www.google.si 127.0.0.1 google.sk 127.0.0.1 www.google.sk 127.0.0.1 google.co.th 127.0.0.1 www.google.co.th 127.0.0.1 google.com.tj 127.0.0.1 www.google.com.tj 127.0.0.1 google.tm 127.0.0.1 www.google.tm 127.0.0.1 google.com.tr 127.0.0.1 www.google.com.tr 127.0.0.1 google.com.tw 127.0.0.1 www.google.com.tw 127.0.0.1 google.com.ua 127.0.0.1 www.google.com.ua 127.0.0.1 google.co.uk 127.0.0.1 www.google.co.uk 127.0.0.1 google.co.vi 127.0.0.1 www.google.co.vi 127.0.0.1 google.com 127.0.0.1 www.google.com 127.0.0.1 google.us 127.0.0.1 www.google.us 127.0.0.1 google.com.pl 127.0.0.1 www.google.com.pl 127.0.0.1 google.co.hu 127.0.0.1 www.google.co.hu 127.0.0.1 google.ge 127.0.0.1 www.google.ge 127.0.0.1 google.kz 127.0.0.1 www.google.kz 127.0.0.1 google.co.uz 127.0.0.1 www.google.co.uz 127.0.0.1 bing.com 127.0.0.1 www.bing.com 127.0.0.1 search.yahoo.com 127.0.0.1 ca.search.yahoo.com 127.0.0.1 ar.search.yahoo.com 127.0.0.1 cl.search.yahoo.com 127.0.0.1 co.search.yahoo.com 127.0.0.1 mx.search.yahoo.com 127.0.0.1 espanol.search.yahoo.com 127.0.0.1 qc.search.yahoo.com 127.0.0.1 ve.search.yahoo.com 127.0.0.1 pe.search.yahoo.com 127.0.0.1 at.search.yahoo.com 127.0.0.1 ct.search.yahoo.com 127.0.0.1 dk.search.yahoo.com 127.0.0.1 fi.search.yahoo.com 127.0.0.1 fr.search.yahoo.com 127.0.0.1 de.search.yahoo.com 127.0.0.1 it.search.yahoo.com 127.0.0.1 nl.search.yahoo.com 127.0.0.1 no.search.yahoo.com 127.0.0.1 ru.search.yahoo.com 127.0.0.1 es.search.yahoo.com 127.0.0.1 se.search.yahoo.com 127.0.0.1 ch.search.yahoo.com 127.0.0.1 uk.search.yahoo.com 127.0.0.1 asia.search.yahoo.com 127.0.0.1 au.search.yahoo.com 127.0.0.1 one.cn.yahoo.com 127.0.0.1 hk.search.yahoo.com 127.0.0.1 in.search.yahoo.com 127.0.0.1 id.search.yahoo.com 127.0.0.1 search.yahoo.co.jp 127.0.0.1 kr.search.yahoo.com 127.0.0.1 malaysia.search.yahoo.com 127.0.0.1 nz.search.yahoo.com 127.0.0.1 ph.search.yahoo.com 127.0.0.1 sg.search.yahoo.com 127.0.0.1 tw.search.yahoo.com 127.0.0.1 th.search.yahoo.com 127.0.0.1 vn.search.yahoo.com 127.0.0.1 images.google.com 127.0.0.1 images.google.ca 127.0.0.1 images.google.co.uk 127.0.0.1 news.google.com 127.0.0.1 news.google.ca 127.0.0.1 news.google.co.uk 127.0.0.1 video.google.com 127.0.0.1 video.google.ca 127.0.0.1 video.google.co.uk 127.0.0.1 blogsearch.google.com 127.0.0.1 blogsearch.google.ca 127.0.0.1 blogsearch.google.co.uk 127.0.0.1 searchservice.myspace.com 127.0.0.1 ask.com 127.0.0.1 www.ask.com 127.0.0.1 search.aol.com 127.0.0.1 search.netscape.com 127.0.0.1 yandex.ru 127.0.0.1 www.yandex.ru 127.0.0.1 yandex.ua 127.0.0.1 www.yandex.ua 127.0.0.1 search.about.com 127.0.0.1 www.verizon.net 127.0.0.1 verizon.net

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  • Matrix inversion in OpenCL

    - by buchtak
    Hi, I am trying to accelerate some computations using OpenCL and part of the algorithm consists of inverting a matrix. Is there any open-source library or freely available code to compute lu factorization (lapack dgetrf and dgetri) of matrix or general inversion written in OpenCL or CUDA? The matrix is real and square but doesn't have any other special properties besides that. So far, I've managed to find only basic blas matrix-vector operations implementations on gpu. The matrix is rather small, only about 60-100 rows and cols, so it could be computed faster on cpu, but it's used kinda in the middle of the algorithm, so I would have to transfer it to host, calculate the inverse, and then transfer the result back on the device where it's then used in much larger computations.

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