Search Results

Search found 393 results on 16 pages for 'scientific'.

Page 12/16 | < Previous Page | 8 9 10 11 12 13 14 15 16  | Next Page >

  • What does your Python development workbench look like?

    - by Fabian Fagerholm
    First, a scene-setter to this question: Several questions on this site have to do with selection and comparison of Python IDEs. (The top one currently is What IDE to use for Python). In the answers you can see that many Python programmers use simple text editors, many use sophisticated text editors, and many use a variety of what I would call "actual" integrated development environments – a single program in which all development is done: managing project files, interfacing with a version control system, writing code, refactoring code, making build configurations, writing and executing tests, "drawing" GUIs, and so on. Through its GUI, an IDE supports different kinds of workflows to accomplish different tasks during the journey of writing a program or making changes to an existing one. The exact features vary, but a good IDE has sensible workflows and automates things to let the programmer concentrate on the creative parts of writing software. The non-IDE way of writing large programs relies on a collection of tools that are typically single-purpose; they do "one thing well" as per the Unix philosophy. This "non-integrated development environment" can be thought of as a workbench, supported by the OS and generic interaction through a text or graphical shell. The programmer creates workflows in their mind (or in a wiki?), automates parts and builds a personal workbench, often gradually and as experience accumulates. The learning curve is often steeper than with an IDE, but those who have taken the time to do this can often claim deeper understanding of their tools. (Whether they are better programmers is not part of this question.) With advanced editor-platforms like Emacs, the pieces can be integrated into a whole, while with simpler editors like gedit or TextMate, the shell/terminal is typically the "command center" to drive the workbench. Sometimes people extend an existing IDE to suit their needs. What does your Python development workbench look like? What workflows have you developed and how do they work? For the first question, please give the main "driving" program – the one that you use to control the rest (Emacs, shell, etc.) the "small tools" -- the programs you reach for when doing different tasks For the second question, please describe what the goal of the workflow is (eg. "set up a new project" or "doing initial code design" or "adding a feature" or "executing tests") what steps are in the workflow and what commands you run for each step (eg. in the shell or in Emacs) Also, please describe the context of your work: do you write small one-off scripts, do you do web development (with what framework?), do you write data-munching applications (what kind of data and for what purpose), do you do scientific computing, desktop apps, or something else? Note: A good answer addresses the perspectives above – it doesn't just list a bunch of tools. It will typically be a long answer, not a short one, and will take some thinking to produce; maybe even observing yourself working.

    Read the article

  • How to recover from finite-state-machine breakdown?

    - by Earl Grey
    My question may seems very scientific but I think it's a common problem and seasoned developers and programmers hopefully will have some advice to avoid the problem I mention in title. Btw., what I describe bellow is a real problem I am trying to proactively solve in my iOS project, I want to avoid it at all cost. By finite state machine I mean this I have a UI with a few buttons, several session states relevant to that UI and what this UI represents, I have some data which values are partly displayed in the UI, I receive and handle some external triggers (represented by callbacks from sensors). I made state diagrams to better map the relevant scenarios that are desirable and alowable in that UI and application. As I slowly implement the code, the app starts to behave more and more like it should. However, I am not very confident that it is robust enough. My doubts come from watching my own thinking and implementation process as it goes. I was confident that I had everything covered, but it was enough to make a few brute tests in the UI and I quickly realized that there are still gaps in the behavior ..I patched them. However, as each component depends and behaves based on input from some other component, a certain input from user or some external source trigers a chain of events, state changes..etc. I have several components and each behave like this Trigger received on input - trigger and its sender analyzed - output something (a message, a state change) based on analysis The problem is, this is not completely selfcontained, and my components (a database item, a session state, some button's state)...COULD be changed, influenced, deleted, or otherwise modified, outside the scope of the event-chain or desirable scenario. (phone crashes, battery is empty phone turn of suddenly) This will introduce a nonvalid situation into the system, from which the system potentially COULD NOT BE ABLE to recover. I see this (althought people do not realize this is the problem) in many of my competitors apps that are on apple store, customers write things like this "I added three documents, and after going there and there, i cannot open them, even if a see them." or "I recorded videos everyday, but after recording a too log video, I cannot turn of captions on them.., and the button for captions doesn't work".. These are just shortened examples, customers often describe it in more detail..from the descriptions and behavior described in them, I assume that the particular app has a FSM breakdown. So the ultimate question is how can I avoid this, and how to protect the system from blocking itself? EDIT I am talking in the context of one viewcontroller's view on the phone, I mean one part of the application. I Understand the MVC pattern, I have separate modules for distinct functionality..everything I describe is relevant to one canvas on the UI.

    Read the article

  • Data Structures usage and motivational aspects

    - by Aubergine
    For long student life I was always wondering why there are so many of them yet there seems to be lack of usage at all in many of them. The opinion didn't really change when I got a job. We have brilliant books on what they are and their complexities, but I never encounter resources which would actually give a good hint of practical usage. I perfectly understand that I have to look at problem , analyse required operations, look for data structure that does them efficiently. However in practice I never do that, not because of human laziness syndrome, but because when it comes to work I acknowledge time priority over self-development. Over time I thought that when I would be better developer I will automatically use more of them - that didn't happen at all or maybe I just didn't. Then I found that the colleagues usually in the same plate as me - knowing more or less some three of data structures and being totally happy about it and refusing to discuss this matter further with me, coming back to conversations about 'cool new languages' 'libraries that do jobs for you' and the joy to work under scrumban etc. I am stuck with ArrayLists, Arrays and SortedMap , which no matter what I do always suffice or either I tweak them to be capable of fulfilling my task. Yes, it might be inefficient but do we really have to care if Intel increases performance over years no matter if we improve our skills? Does new Xeon or IBM machines really care what we use? What if I like build things, but I am not particularly excited whether it is n log(n) or just n? Over twenty years the processing power increased enormously, which gives us freedom of not being critical about which one to use? On top of that new more optimized languages appear which support multiple cores more efficiently. To be more specific: I would like to find motivational material on complex real areas/cases of possible effective usages of data structures. I would be really grateful if you would provide relevant resources. There is similar question ,but in the end the links again mostly describe or do dumb example(vehicles, students or holy grail quest - yes, very relevant) them and people keep referring to the "scenario decides the data structure to use". I want to know these complex scenarios to be able to identify similarities to my scenario and then use them. The complex scenarios where it really matters and not necessarily of quantitive nature. It seems that data structures only concern is efficiency and nothing else? There seems to be no particular convenience for developer in use one over another. (only when I found scientific resources on why exactly simple carbohydrates are evil I stopped eating sugar and candies completely replacing it with less harmful fruits - I hope you can see the analogy)

    Read the article

  • Canonicalization issue regarding academic URL vs. blog URL

    - by user5395
    I'm sorry if what I am about to write is long-winded. I only wish to be clear. I am an academic in the scientific community. I maintain a web site for my research, teaching, and other professional activities. Until recently, the content for this site was hosted in a directory on my university department's own server. The address is of the typical form (universityname).edu/~(myusername) I decided that I wanted to use WordPress in order to host and manage my page. So I set up a WordPress.com blog and then replaced the index.html file in (universityname).edu/~(myusername) with a new one consisting of a single frame, containing the WordPress.com blog. Now when a user visits (universityname).edu/~(myusername), he or she sees the blog instead. This has been pretty nice because, even when the user clicks on links between pages or posts in the blog, the only thing showing up in the address bar of the browser is www.(universityname).edu/~(myusername), because the blog is constrained to a frame. However, the effect of this change on the search side of things has not been so kind to me. Before, when someone searched for my name in Google, the first result was always (universityname).edu/~(myusername). This is the most desirable outcome, for professional reasons. (Having my academic URL come up first suggests that I am an accredited professional, and not just some crank with a blog!) But now, Google seems to have canonicalized my web presence under the blog's WordPress.com address. It has completely forgotten about my academic URL and considers the WordPress.com address to be the best address representing me on the web. Unfortunately, WordPress.com doesn't support the canonical tag, so I can't tell the blog to advertise itself as my academic URL in the header. (It doesn't seem to help at all that I have used the WordPress.com dashboard to turn on no-indexing of the blog.) One obvious solution would be to use the departmental server to host my content again, and use a local installation of the WordPress platform. For reasons beyond my control, the platform will not be deployed on the departmental server at this time. Another solution would be to use shared hosting with WordPress.org support, because the WordPress.org platform does support the canonical tag (albeit via a plug-in). But this seems to usually require purchasing a domain name and other fees, and there is no guarantee that Google will listen to the canonical tag (it might use whatever domain name I end up with instead). Is there a way I can more cleverly integrate the WordPress.com blog into a page hosted on my department's server? Is there some PHP code I can write to retrieve the blog's contents in a way that Google won't treat as a link / "perceive" the blog? Please note: I am a PHP novice at best. I just feel there should be a simpler solution to all this, within the constraints of what I have described above. Thanks!

    Read the article

  • Purple Cows, Copernicus, and Shampoo – Lessons in Customer Experience

    - by Christina McKeon
    What makes a great customer experience? And, why should you or your organization care? These are the questions that set the stage for the Oracle Customer Experience Summit, which kicked off yesterday in San Francisco. Day 1: The first day was filled with demos and insights from customer experience experts and Oracle customers sharing what it takes to deliver great customer experiences. Author Seth Godin delivered an entertaining presentation that included an in-depth exploration of the always-connected, always-sharing experience revolution that we are witnessing and yes, talked about the purple cow. It turns out that customer experience is your way to be the purple cow. Before everyone headed out to see Pearl Jam and Kings of Leon at the Oracle customer appreciation event, the day wrapped up with a discussion around building a customer-centric culture. Where do you start? Whom does it involve? What are some pitfalls to avoid? Day 2: The second day addressed the details behind all the questions brought up at the end of Day 1. Before you start on a customer experience initiative, Paul Hagen noted that you must understand you will forge a path similar to Copernicus. You will be proposing ideas and approaches that challenge current thinking in your organization. Just as Copernicus' heliocentric theory started a scientific revolution, your customer-centric efforts will start an experience revolution. If you think customer experience is like a traditional marketing approach, think again. It’s not about controlling your customers and leading them where you want them to go. It might sound like heresy to some, but your customers are already in control, whether or not your company realizes and acknowledges it. And, to survive and thrive, you'll have to focus on customers by thinking outside-in and working towards a brand that is better and more authentic. We learned how Vail Resorts takes this customer-centric approach. Employees must experience the mountain themselves and understand the experience from the guest’s standpoint. This has created a culture where employees do things for guests that are not expected. We also learned a valuable lesson in designing and innovating customer-centered experiences from Kerry Bodine. First you make the thing, and then you make the thing right. In this case, the thing is customer experience. Getting customer experience right means iterative prototyping and testing of your ideas. This is where shampoo comes in—think lather, rinse, repeat. Be prepared to keep repeating until the customer experience is right. Many of these sessions will be posted to YouTube in the coming weeks so be sure to subscribe to our CX channel.

    Read the article

  • What is the difference between development and R&D?

    - by MainMa
    I was asked by a colleague to explain clearly the difference between ordinary development and research and development (R&D) and was unable to do it. After reading Wikipedia, I still don't have the precise answer. According to Wikipedia (slightly modified): There are two primary models: In one model, the primary function is to develop new products; in the other model, the primary function is to discover and create new knowledge about scientific and technological topics for the purpose of uncovering and enabling development of valuable new products, processes, and services. The first model is confusing. Does it mean that development (not R&D) consists exclusively in adding new features to a product, solving bugs and doing maintenance? What if something which was previously developed as a new feature becomes a separate product? The second model is less confusing, but still, how to qualify whether something is new knowledge or existent knowledge which is just rediscovered? Later, Wikipedia adds that ordinary development is different from R&D because of its: nearly immediate profit or immediate improvement. It's still not clear enough. How to qualify "nearly immediate profit"? What if a task has an immediate profit but requires heavy research? Or if it is basic but has uncertain profit, like the enforcement of a common style over the codebase? For example, does it belong to development or R&D to: Develop an engine which abstracts the access to the database, simplifying and shortening enormously the code of other applications (existent or ones which will be written in future) which should access to the database? Establish a new service-oriented architecture for the entire organization of company resources, in order to move from a bunch of separate and autonomous applications to a set of well-organized, interconnected web services, like what is used by Amazon? Design a new communication protocol to allow faster replication of data between two data centers of the company? Conceive a new type of software testing while working on a specific product, knowing that this type of testing will improve/simplify the testing process? Prove that Functional programming is more appropriate than OOP for a specific application, based on evidence, logic and previous experience? Enhance the existent application by adding gestures on tactile screens, after doing studies and testing that shows that those gestures improve the productivity of the users by a ratio of at least 1.4 for a precise set of tasks? Find a way to strongly enhance the Power usage effectiveness (PUE) of a data center? Create a Domain-Specific Language (DSL)? In short, how could I determine whether I'm doing R&D while working on something?

    Read the article

  • What Precalculus knowledge is required before learning Discrete Math Computer Science topics?

    - by Ein Doofus
    Below I've listed the chapters from a Precalculus book as well as the author recommended Computer Science chapters from a Discrete Mathematics book. Although these chapters are from two specific books on these subjects I believe the topics are generally the same between any Precalc or Discrete Math book. What Precalculus topics should one know before starting these Discrete Math Computer Science topics?: Discrete Mathematics CS Chapters 1.1 Propositional Logic 1.2 Propositional Equivalences 1.3 Predicates and Quantifiers 1.4 Nested Quantifiers 1.5 Rules of Inference 1.6 Introduction to Proofs 1.7 Proof Methods and Strategy 2.1 Sets 2.2 Set Operations 2.3 Functions 2.4 Sequences and Summations 3.1 Algorithms 3.2 The Growths of Functions 3.3 Complexity of Algorithms 3.4 The Integers and Division 3.5 Primes and Greatest Common Divisors 3.6 Integers and Algorithms 3.8 Matrices 4.1 Mathematical Induction 4.2 Strong Induction and Well-Ordering 4.3 Recursive Definitions and Structural Induction 4.4 Recursive Algorithms 4.5 Program Correctness 5.1 The Basics of Counting 5.2 The Pigeonhole Principle 5.3 Permutations and Combinations 5.6 Generating Permutations and Combinations 6.1 An Introduction to Discrete Probability 6.4 Expected Value and Variance 7.1 Recurrence Relations 7.3 Divide-and-Conquer Algorithms and Recurrence Relations 7.5 Inclusion-Exclusion 8.1 Relations and Their Properties 8.2 n-ary Relations and Their Applications 8.3 Representing Relations 8.5 Equivalence Relations 9.1 Graphs and Graph Models 9.2 Graph Terminology and Special Types of Graphs 9.3 Representing Graphs and Graph Isomorphism 9.4 Connectivity 9.5 Euler and Hamilton Ptahs 10.1 Introduction to Trees 10.2 Application of Trees 10.3 Tree Traversal 11.1 Boolean Functions 11.2 Representing Boolean Functions 11.3 Logic Gates 11.4 Minimization of Circuits 12.1 Language and Grammars 12.2 Finite-State Machines with Output 12.3 Finite-State Machines with No Output 12.4 Language Recognition 12.5 Turing Machines Precalculus Chapters R.1 The Real-Number System R.2 Integer Exponents, Scientific Notation, and Order of Operations R.3 Addition, Subtraction, and Multiplication of Polynomials R.4 Factoring R.5 Rational Expressions R.6 Radical Notation and Rational Exponents R.7 The Basics of Equation Solving 1.1 Functions, Graphs, Graphers 1.2 Linear Functions, Slope, and Applications 1.3 Modeling: Data Analysis, Curve Fitting, and Linear Regression 1.4 More on Functions 1.5 Symmetry and Transformations 1.6 Variation and Applications 1.7 Distance, Midpoints, and Circles 2.1 Zeros of Linear Functions and Models 2.2 The Complex Numbers 2.3 Zeros of Quadratic Functions and Models 2.4 Analyzing Graphs of Quadratic Functions 2.5 Modeling: Data Analysis, Curve Fitting, and Quadratic Regression 2.6 Zeros and More Equation Solving 2.7 Solving Inequalities 3.1 Polynomial Functions and Modeling 3.2 Polynomial Division; The Remainder and Factor Theorems 3.3 Theorems about Zeros of Polynomial Functions 3.4 Rational Functions 3.5 Polynomial and Rational Inequalities 4.1 Composite and Inverse Functions 4.2 Exponential Functions and Graphs 4.3 Logarithmic Functions and Graphs 4.4 Properties of Logarithmic Functions 4.5 Solving Exponential and Logarithmic Equations 4.6 Applications and Models: Growth and Decay 5.1 Systems of Equations in Two Variables 5.2 System of Equations in Three Variables 5.3 Matrices and Systems of Equations 5.4 Matrix Operations 5.5 Inverses of Matrices 5.6 System of Inequalities and Linear Programming 5.7 Partial Fractions 6.1 The Parabola 6.2 The Circle and Ellipse 6.3 The Hyperbola 6.4 Nonlinear Systems of Equations

    Read the article

  • How employable am I as a programmer?

    - by dsimcha
    I'm currently a Ph.D. student in Biomedical Engineering with a concentration in computational biology and am starting to think about what I want to do after graduate school. I feel like I've accumulated a lot of programming skills while in grad school, but taken a very non-traditional path to learning all this stuff. I'm wondering whether I would have an easy time getting hired as a programmer and could fall back on that if I can't find a good job directly in my field, and if so whether I would qualify for a more prestigious position than "code monkey". Things I Have Going For Me Approximately 4 years of experience programming as part of my research. I believe I have a solid enough grasp of the fundamentals that I could pick up new languages and technologies pretty fast, and could demonstrate this in an interview. Good math and statistics skills. An extensive portfolio of open source work (and the knowledge that working on these projects implies): I wrote a statistics library in D, mostly from scratch. I wrote a parallelism library (parallel map, reduce, foreach, task parallelism, pipelining, etc.) that is currently in review for adoption by the D standard library. I wrote a 2D plotting library for D against the GTK Cairo backend. I currently use it for most of the figures I make for my research. I've contributed several major performance optimizations to the D garbage collector. (Most of these were low-hanging fruit, but it still shows my knowledge of low-level issues like memory management, pointers and bit twiddling.) I've contributed lots of miscellaneous bug fixes to the D standard library and could show the change logs to prove it. (This demonstrates my ability read other people's code.) Things I Have Going Against Me Most of my programming experience is in D and Python. I have very little to virtually no experience in the more established, "enterprise-y" languages like Java, C# and C++, though I have learned a decent amount about these languages from small, one-off projects and discussions about language design in the D community. In general I have absolutely no knowledge of "enterprise-y" technlogies. I've never used a framework before, possibly because most reusable code for scientific work and for D tends to call itself a "library" instead. I have virtually no formal computer science/software engineering training. Almost all of my knowledge comes from talking to programming geek friends, reading blogs, forums, StackOverflow, etc. I have zero professional experience with the official title of "developer", "software engineer", or something similar.

    Read the article

  • PostgreSQL lots of writes

    - by strife911
    Hi, I am using postgreSQL for a scientific application (unsupervised clustering). The python program is multi-threaded so that each thread manages its own postmaster process (one per core). Hence, their is a lot of concurrency. Each thread-process loop infinitely though two SQL queries. The first is for reading, the second is for writing. The read operation considers 500 time the amount of rows the write operation considers. Here is the output of dstat: ----total-cpu-usage---- ------memory-usage----- -dsk/total- --paging-- --io/total- usr sys idl wai hiq siq| used buff cach free| read writ| in out | read writ 4 0 32 64 0 0|3599M 63M 57G 1893M|1524k 16M| 0 0 | 98 2046 1 0 35 64 0 0|3599M 63M 57G 1892M|1204k 17M| 0 0 | 68 2062 2 0 32 66 0 0|3599M 63M 57G 1890M|1132k 17M| 0 0 | 62 2033 2 1 32 65 0 0|3599M 63M 57G 1904M|1236k 18M| 0 0 | 80 1994 2 0 31 67 0 0|3599M 63M 57G 1903M|1312k 16M| 0 0 | 70 1900 2 0 37 60 0 0|3599M 63M 57G 1899M|1116k 15M| 0 0 | 71 1594 2 1 37 60 0 0|3599M 63M 57G 1898M| 448k 17M| 0 0 | 39 2001 2 0 25 72 0 0|3599M 63M 57G 1896M|1192k 17M| 0 0 | 78 1946 1 0 40 58 0 0|3599M 63M 57G 1895M| 432k 15M| 0 0 | 38 1937 I am pretty sure I could write more often than that for I have seen it write up to 110-140M on dstat. How can I optimize this process?

    Read the article

  • Snort/Barnyard2 Logging

    - by Eric
    I need some help with my Snort/Barnyard2 setup. My goal is to have Snort send unified2 logs to Barnyard2 and then have Barnyard2 send the data to other locations. Here is my currrent setup. OS Scientific Linux 6 Snort Version 2.9.2.3 Barnyard2 Version 2.1.9 Snort command snort -c /etc/snort/snort.conf -i eth2 & Barnyard2 command /usr/local/bin/barnyard2 -c /etc/snort/barnyard2.conf -d /var/log/snort -f snort.log -w /var/log/snort/barnyard.waldo & snort.conf output unified2: filename snort.log, limit 128 barnyard2.conf output alert_syslog: host=127.0.0.1 output database: log, mysql, user=snort dbname=snort password=password host=localhost With this setup, barnyard2 is showing all of the correct information in the database and I'm using BASE to view it on the web GUI. I was hoping to be able to send the full packet data to syslog with barnyard2 but after reading around, it seems that it is impossible to do that. So I then started trying to modify the snort.conf file and add lines like "output alert_full: alert.full". This definitely gave me a lot more information but still not the full packet data like I want. So my question is, is there anyway I can use barnyard2 to send the full packet data of alerts to a human readable file? Since I can't send it directly to syslog, I can create another process to take the data from that file and ship it off to another server. If not, what flags and/or snort.conf configuration would you recommend to get the most data possible but still be able to handle quite a bit of traffic? In the end of it all, these alerts will be shipped to a central server via a SSH tunnel. I'm trying to stay away from databases.

    Read the article

  • Using 1920x1200 mode on SyncMaster T260HD in Linux

    - by dagorym
    I just got a Samsung SyncMaster T260HD monitor. It works straight out of the box with Windows but I can't seem to get it to work with Linux, which is my primary OS for day to day work. The computer boots up but when going into graphical mode on Linux the monitor gives me a "Mode not supported" error and doesn't display anything. I booted up windows and, using PowerStrip, grabbed the exact ModeLine that should be used to get the equivalent setting in Linux and added it to my xorg config file but it doesn't seem to help. the ModeLine is: ModeLine "1920x1200" 153.9 1920 1984 2016 2080 1200 1203 1209 1235 +hsync -vsync This is the modeline for the working display settings in windows but it doesn't seem to work in Linux My complete entry in the xorg.conf file for the monitor is Section "Monitor" Identifier "Monitor0" ModelName "SyncMaster" DisplaySize 518 324 HorizSync 30.0 - 81.0 VertRefresh 56.0 - 75.0 Option "dpms" ModeLine "1920x1200" 153.9 1920 1984 2016 2080 1200 1203 1209 1235 +hsync -vsync EndSection I'm running Scientific Linux 5.4 (clone of Redhat Enterprise Linux 5.4) but I've tried booting with a recent Linux Mint Distro as well as Ubuntu 9.04 and had the same problem. Any suggestions on other things I should try or might be missing? If anyone's gotten this to work I'd love to know. Thanks.

    Read the article

  • How can I bridge a VM to a remote network?

    - by asciiphil
    I have a system running QEMU/KVM (via libvirt). One of its VMs needs to have a presence on a subnet that is not local to the VM host. I have a Linux system on the remote subnet. Is there a way to set up some sort of tunneled bridge to cause the VM to appear present on the remote system? This will be a temporary situation (hopefully just until the VM owner can configure their system) and network performance and long-term maintainability aren't really issues. To give some more concrete information: My VM host has IP address 192.168.54.155/24. The VM has IP address 192.168.65.71/24. I have a remote system at 192.168.65.254/24. Both the VM host and remote system are running Scientific Linux 6.5. I do not control the network or routing in between the VM host and remote system. I do not have access to the guest OS on the VM. I would like traffic to the VM's IP address to end up at the VM even though its host isn't directly connected to the appropriate network. I've tried using iproute2's tunnelling, but Linux won't let me add a tunnel to a bridge. I've considered using some sort of iptables mangling to route traffic over the tunnel and make the VM think it's on the right network, but I'm not sure whether there are better approaches. What's the best way to accomplish this hack?

    Read the article

  • Is there a fix to display 0 when arithmetic underflow occurs on the Windows 7 calculator?

    - by Pascal Qyy
    I have a problem that exasperates me: When I take the Windows 7 calculator in standard mode, if I do 4, then v (square root), the result is 2 Fine. But, at this point, if I do - (minus), then 2, the result is -1,068281969439142e-19 instead of 0! OK, I know about ? (machine epsilon), and yes, -1,068281969439142e-19 is less than the 64 bits ? (1.11e-16), so, we have an arithmetic underflow, in other words in this case: 0. Great, my computer is able to represent subnormal numbers instead of just flush to zero when this happens, and it seems that it is an improvement! Subnormal values fill the underflow gap with values where the absolute distance between them are the same as for adjacent values just outside of the underflow gap. This is an improvement over the older practice to just have zero in the underflow gap, and where underflowing results were replaced by zero (flush to zero). BUT: this result is false! when you try to explain the concept of the square root to a child and you end up with this kind of result, it only complicates your task... what is the point to represent subnormal numbers in a standard, non scientific calculator? So, is there a way to fix this?

    Read the article

  • Filtered Router Interface

    - by jviotti
    I'm having some problems with a Scientific-Atlanta DPR2320R2. In specific with the WIFI. A few months ago I changed its password and username and now I can't remember. So I tried cracking it with Hydra but it drove things worse. Content of webadmin was rendered partial, and threw lot of errors. I then reseted the router. I found myself abled to browse the web with ethernet-connected pc. Wifi is configured by registering the device's MAC Address, and indeed the router has been reseted and register MAC address were lost. No device could connect to wifi. In fact, the device does not even recognize the network. I tried the pointing to 192.168.0.1 to restablish the MAC's. But I couldn't connect to the router access point. Tried listing up hosts: $ nmap -sP 192.168.0.0/24 Starting Nmap 5.00 ( http://nmap.org ) at 2012-12-11 01:18 ART Host 192.168.0.1 is up (0.0018s latency). Host 192.168.0.11 is up (0.00025s latency). Nmap done: 256 IP addresses (2 hosts up) scanned in 59.62 seconds Then checked 192.168.0.1 was really up by sending pings. It responded to all my pings. I quick-scanned the access point: $ nmap 192.168.0.1 Starting Nmap 5.00 ( http://nmap.org ) at 2012-12-11 01:08 ART Interesting ports on 192.168.0.1: Not shown: 999 closed ports PORT STATE SERVICE 80/tcp filtered http Nmap done: 1 IP address (1 host up) scanned in 6.73 seconds Look the state of the port 80: FILTERED. I'm pretty confused now. Any suggestion would be appreciated. Thanks in advance.

    Read the article

  • PostgreSQL 8.4 - Tablespace Optimization

    - by FloE
    I'm currently running a PostgreSQL Database with about 1.5 billion rows / 500 GB of data (including indices). There are several schemata: on for the (read only, irregular changes / updates) 'core-model' and one for every user (about 20 persons). The users can access the core and store data in their own schema, so everything is located in one database. The server runs with CentOS and PostgreSQL 8.4 and is used for scientific studies, exploration etc and is running quite well. These days an upgrade of the DB storage hard disks arrive - all with the same performance as the old ones. I'm looking for the best way to distribute the data on these disks. It would be possible to separate frequently used objects (the core-data) from the user schemata, but I'm not sure if this is really worth the effort. It seems to be a much better idea to move the WAL files (pg_xlog directory) to its own partition. http://www.postgresql.org/docs/8.4/static/wal-internals.html What are your opinions? Are there any tablespace- or partitioning-related performance documentations / benchmarks?

    Read the article

  • Getting rsync to move file from source to destination ?

    - by fabien-barbier
    Is rsync is a good choice for my project ? I have to : - copy files from source to destination folder via SSH, - be sure all files are copied, - delete source files after copy. - if I have conflict name, I have to rename files. It looks like I can use option : --remove-source-files (to delete source files) But how rsync manage conflict, can I had rules ? Use case on my project : I run scientific calculation on server A and results are inserted in folder "process", for each calculation I have a repository like this : /process/calc1. Now I would like to transfer repository "/calc1" to server B (I get /process/calc1), and delete "calc1" from server A. ...During another calculation I get "/process/calc2" on server A, the idea is also to move "calc2" in "/process/" directory on server B, then I have now on server B : - /process/calc1 - /process/calc2 (and /process/ on server A is empty). How rsync will manage conflict (on server B) if I have another folder like "/process/calc1" in server A after a new calculation (if "/process/calc1" already exist on server B) ? Is it possible to add rules with rsync, and rename "/process/calc1" by "process/calc1R2" in server B ? And so on (ex:calc1R3) ? Thanks.

    Read the article

  • Solution to easily share large files with non-tech-savvy users?

    - by Tim
    Hey all, We've got a server setup at work which we'd like to use to exchange large files with known clients easily. We're looking into software to facilitate this, but somewhow typing "large file hosting" into Google gives questionable results.. ;) We've come up with the following requirements, and I hope any of you can points us in the direction of a solution that offers this functionality, or is malleable to our needs. Synchronization / revision management is of no concern, it's mostly single large (up to 1+ GB) file uploads & downloads we'll need. We'd like to make the downloads expire & be removed after a certain number of days / downloads, to limit the amount of cleanup we'd have to do. The data files exchanged sometimes hold confidential information, so the URLs generated should be random and not publicly visible. Our users are of the less technically savvy variety, so a simple webform would be best over a desktop client (because we also have to support a mix of operating systems). As for use of the system we'd either like to send out generated random URLs for them to upload their files, or have an easy way manage & expire users. Works on a linux (Ubuntu) server (so nothing .Net-related please) Does anyone know of software that fits the above criteria? We've already seen a few instances of this within the scientific community, but nothing we could use directly.. Best regards, Tim

    Read the article

  • Solution to easily share large files with non-tech-savvy users?

    - by Tim
    Hey all, We've got a server setup at work which we'd like to use to exchange large files with known clients easily. We're looking into software to facilitate this, but somewhow typing "large file hosting" into Google gives questionable results.. ;) We've come up with the following requirements, and I hope any of you can points us in the direction of a solution that offers this functionality, or is malleable to our needs. Synchronization / revision management is of no concern, it's mostly single large (up to 1+ GB) file uploads & downloads we'll need. We'd like to make the downloads expire & be removed after a certain number of days / downloads, to limit the amount of cleanup we'd have to do. The data files exchanged sometimes hold confidential information, so the URLs generated should be random and not publicly visible. Our users are of the less technically savvy variety, so a simple webform would be best over a desktop client (because we also have to support a mix of operating systems). As for use of the system we'd either like to send out generated random URLs for them to upload their files, or have an easy way manage & expire users. Works on a linux (Ubuntu) server (so nothing .Net-related please) Does anyone know of software that fits the above criteria? We've already seen a few instances of this within the scientific community, but nothing we could use directly.. Best regards, Tim

    Read the article

  • Creating a Jenkins build farm in a hands-off manner?

    - by user183394
    My colleague and I have set up and run Jenkins on a KVM guest running Ubuntu 12.04 with good results for a while now. We are thinking about deploying a cluster of Jenkins CI hosts in master/slave configuration, with the libvirt slave plugin to keep our hardware count low. Our environment is strictly Linux (CentOS, Scientific Linux, Fedora, and Ubuntu). Both of us are competent in setting up large clusters. We typically use tools like cobbler + a configuration management tool (Puppet, Chef, and alike) to set up a large number of machines (physical and/or virtual) hands off (hundreds of nodes in less than an hour typical). We would like to do the same for nodes running Jenkins. But the step by step guide doesn't give us any clues in this regard. I did see a Multi-slave config plugin. But, being used to dealing with hundreds or more machines completely hands-off, clicking the UI for many machines just doesn't feel right. Can someone point to us a reference that talks about how to set up large cluster of Jenkins CI hosts more in the hands-off way?

    Read the article

  • What is the proper way of debugging a slow Windows installation?

    - by Niklas
    You know the drill - you've been asked to check why you cousin's computer is running slow. I was there yesterday. Being a Mac user since 2007 I haven't really dug deep in Windows internals in the past five years. Googling for answers reveals many, many different answers: broken registry, spyware, antivirus program, fragmented disk, turning of visual effects etc. In this particular case I was asked to look at a two year old HP laptop with Vista. Windows was running incredibly slow and even opening up a new explorer window took almost a minute. I ended up doing everything of the above: running cc cleaner, defragmenting the disk, turning off visual effects, turning off norton and a bunch of other things people believe have an impact on Windows performance. Now I'd like to understand this in depth. Is there a proper, "scientific" if you so will, way of debugging and understanding where the problem with a slow running Windows installation lies? (In my particular case this concerned Windows Vista but let's try to create general guide for XP and Windows 7 too). To me, it seems wrong to just run a bunch of different tools without understanding the underlying cause of the error.

    Read the article

  • Remote offscreen rendering

    - by redmoskito
    My research lab recently added a server that has a beefy NVIDIA graphics card, which we would like to use to do scientific computations. Since it isn't a workstation, we'll have to run our jobs remotely, over an ssh connection. Most of our applications require doing opengl rendering to an offscreen buffer, then doing image analysis on the result in CUDA. My initial investigation suggests that X11 forwarding is a bad idea, because opengl rendering will occur on the client machine (or rather the X11 server--what a confusing naming convention!) and will suffer network bottlenecks when sending our massive textures. We will never need to display the output, so it seems like X11 forwarding shouldn't be necessary, but Opengl needs the $DISPLAY to be set to something valid or our applications won't run. I'm sure render farms exist that do this, but how is it accomplished? I think this is probably a simple X11 configuration issue, but I'm too unfamiliar with it to know where to start. We're running Ubuntu server 10.04, with no gdm, gnome, etc installed. However, xserver-xorg package is installed.

    Read the article

  • Are there any benchmarks showing difference between hardware virtualisation enabled/disabled?

    - by Wil
    I have a 13" sub-laptop/large-netbook, it has an AMD Athlon Neo X2 L335, and I chose this one because it supports hardware virtualisation. In the end, I hardly do any virtualisation on it, however, when I do... it is fast. To my shock, I went in to the BIOS and saw that virtualisation was disabled! I turned this on and, I see no speed difference.... or at least none that I can tell. I do not have time to do a full set of benchmarks - and I run quite a bit of software on the host, so it wouldn't be scientific. I have searched quite a few places and I just can not find any benchmarks showing the difference of virtualisation bit enabled/disabled on the same hardware. Does anyone have any benchmarks they have seen that they can share? In addition, I know there was an uproar a while ago as Sony disable the hardware virtualisation on some models and only offer it in their higher models as a premium feature, however, apart from forcing an up-sell, are there any benefits to having it disabled e.g. battery/heat? I just can't find any information and can't work out why it would be disabled by default. Edit--- To add, The only thing I can find is that without it, you can not perform x64 virtualisation as fast. This is the only down side I can find. However, if this is the only difference, then I am still interested in the second part of the question - why offer the option to disable it?

    Read the article

  • How to reproject a shapefile from WGS 84 to Spherical/Web Mercator projection.

    - by samkea
    Definitions: You will need to know the meaning of these terms below. I have given a small description to the acronyms but you can google and know more about them. #1:WGS-84- World Geodetic Systems (1984)- is a standard reference coordinate system used for Cartography, Geodesy and Navigation. #2: EPGS-European Petroleum Survey Group-was a scientific organization with ties to the European petroleum industry consisting of specialists working in applied geodesy, surveying, and cartography related to oil exploration. EPSG::4326 is a common coordinate reference system that refers to WGS84 as (latitude, longitude) pair coordinates in degrees with Greenwich as the central meridian. Any degree representation (e.g., decimal or DMSH: degrees minutes seconds hemisphere) may be used. Which degree representation is used must be declared for the user by the supplier of data. So, the Spherical/Web Mercator projection is referred to as EPGS::3785 which is renamed to EPSG:900913 by google for use in googlemaps. The associated CRS(Coordinate Reference System) for this is the "Popular Visualisation CRS / Mercator ". This is the kind of projection that is used by GoogleMaps, BingMaps,OSM,Virtual Earth, Deep Earth excetra...to show interactive maps over the web with thier nearly precise coordinates.  Reprojection: After reading alot about reprojecting my coordinates from the deepearth project on Codeplex, i still could not do it. After some help from a colleague, i got my ball rolling.This is how i did it. #1 You need to download and open your shapefile using Q-GIS; its the one with the biggest number of coordinate reference systems/ projections. #2 Use the plugins menu, and enable ftools and the WFS plugin. #3 Use the Vector menu--> Data Management Tools and choose define current projection. Enable, use predefined reference system and choose WGS 84 coodinate system. I am personally in zone 36, so i chose WGS84-UTM Zone 36N under ( Projected Coordinate Systems--> Universal Transverse Mercator) and click ok. #4 Now use the Vector menu--> Data Management Tools and choose export to new projection. The same dialog will pop-up. Now choose WGS 84 EPGS::4326 under Geodetic Coordinate Systems. My Input user Defined Spatial Reference System should looks like this: +proj=tmerc +lat_0=0 +lon_0=33 +k=0.9996 +x_0=500000 +y_0=200000 +ellps=WGS84 +datum=WGS84 +units=m +no_defs Your Output user Defined Spatial Reference System should look like this: +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs Browse for the place where the shapefile is going to be and give the shapefile a name(like origna_reprojected). If it prompts you to add the projected layer to the TOC, accept. There, you have your re-projected map with latitude and longitude pair of coordinates. #5 Now, this is not the actual Spherical/Web Mercator projection, but dont worry, this is where you have to stop. All the other custom web-mapping portals will pick this projection and transform it into EPGS::3785 or EPSG:900913 but the coordinates will still remain as the LatLon pair of the projected shapefile. If you want to test, a particular know point, Q-GIS has a lot of room for that. Go ahead and test it.

    Read the article

  • From NaN to Infinity...and Beyond!

    - by Tony Davis
    It is hard to believe that it was once possible to corrupt a SQL Server Database by storing perfectly normal data values into a table; but it is true. In SQL Server 2000 and before, one could inadvertently load invalid data values into certain data types via RPC calls or bulk insert methods rather than DML. In the particular case of the FLOAT data type, this meant that common 'special values' for this type, namely NaN (not-a-number) and +/- infinity, could be quite happily plugged into the database from an application and stored as 'out-of-range' values. This was like a time-bomb. When one then tried to query this data; the values were unsupported and so data pages containing them were flagged as being corrupt. Any query that needed to read a column containing the special value could fail or return unpredictable results. Microsoft even had to issue a hotfix to deal with failures in the automatic recovery process, caused by the presence of these NaN values, which rendered the whole database inaccessible! This problem is history for those of us on more current versions of SQL Server, but its ghost still haunts us. Recently, for example, a developer on Red Gate’s SQL Response team reported a strange problem when attempting to load historical monitoring data into a SQL Server 2005 database via the C# ADO.NET provider. The ratios used in some of their reporting calculations occasionally threw out NaN or infinity values, and the subsequent attempts to load these values resulted in a nasty error. It turns out to be a different manifestation of the same problem. SQL Server 2005 still does not fully support the IEEE 754 standard for floating point numbers, in that the FLOAT data type still cannot handle NaN or infinity values. Instead, they just added validation checks that prevent the 'invalid' values from being loaded in the first place. For people migrating from SQL Server 2000 databases that contained out-of-range FLOAT (or DATETIME etc.) data, to SQL Server 2005, Microsoft have added to the latter's version of the DBCC CHECKDB (or CHECKTABLE) command a DATA_PURITY clause. When enabled, this will seek out the corrupt data, but won’t fix it. You have to do this yourself in what can often be a slow, painful manual process. Our development team, after a quizzical shrug of the shoulders, simply decided to represent NaN and infinity values as NULL, and move on, accepting the minor inconvenience of not being able to tell them apart. However, what of scientific, engineering and other applications that really would like the luxury of being able to both store and access these perfectly-reasonable floating point data values? The sticking point seems to be the stipulation in the IEEE 754 standard that, when NaN is compared to any other value including itself, the answer is "unequal" (i.e. FALSE). This is clearly different from normal number comparisons and has repercussions for such things as indexing operations. Even so, this hardly applies to infinity values, which are single definite values. In fact, there is some encouraging talk in the Connect note on this issue that they might be supported 'in the SQL Server 2008 timeframe'. If didn't happen; SQL 2008 doesn't support NaN or infinity values, though one could be forgiven for thinking otherwise, based on the MSDN documentation for the FLOAT type, which states that "The behavior of float and real follows the IEEE 754 specification on approximate numeric data types". However, the truth is revealed in the XPath documentation, which states that "…float (53) is not exactly IEEE 754. For example, neither NaN (Not-a-Number) nor infinity is used…". Is it really so hard to fix this problem the right way, and properly support in SQL Server the IEEE 754 standard for the floating point data type, NaNs, infinities and all? Oracle seems to have managed it quite nicely with its BINARY_FLOAT and BINARY_DOUBLE types, so it is technically possible. We have an enterprise-class database that is marketed as being part of an 'integrated' Windows platform. Absurdly, we have .NET and XPath libraries that fully support the standard for floating point numbers, and we can't even properly store these values, let alone query them, in the SQL Server database! Cheers, Tony.

    Read the article

  • InSync12 and Australia Visits: UX is Global, Regional, Everywhere!

    - by ultan o'broin
    I attended the Australian Oracle User Group (AUSOUG) and Quest International User Group's InSync12 event in Melbourne, Australia: the user group conference for Oracle products in the ANZ region. I demoed Oracle Fusion Applications and then presented how Oracle crafted the world class Fusion Apps user experience (UX). I explained about the Oracle user experience design pattern strategy of uptake for all apps, not just Fusion, and what our UX pattern externalization strategy means for customers, partners, and ADF developers. A great conference, lots of energy, the InSync12 highlights for me were Oracle's Senior Vice President Cliff Godwin’s fast-moving Oracle E-Business Suite (EBS) roadshow with the killer Oracle Endeca user experience uptake, and Oracle ADF product outreachmeister Chris Muir’s (@chriscmuir) session on Oracle ADF Mobile solution and his hands-on mobile app development showing how existing ADF/JDev skills can build a secure, code once-deploy-to-many-device hybrid app solution in minutes. Cliff Godwin shows off the Oracle Endeca integration with Oracle E-Business Suite. Chris Muir talked the talk and then walked the walked with Oracle ADF Mobile. Applications UX was mixing it up with the crowd at InSync12 too, showing off cool mobile UX solutions, gathering data for future innovations, and engaging with EBS, JD Edwards, and PeopleSoft apps customers and partners. User conferences such as InSync12 are an important part of our Oracle Applications UX user-centered design process, giving real apps users the opportunity to make real inputs and a way for us to watch and to listen to their needs and wants and get views on current and emerging UX too. Eric Stilan (@icondaddy) of Applications UX uses an iPad to gather feedback on the latest UX designs from conference attendees. While in Melbourne, I also visited impressive Oracle partner, Callista for a major ADF and UX pow-wow, and was the er, star of a very proactive event hosted by another partner Park Lane Information Technology (coordinated by Bambi Price (@bambiprice) of ODTUG) where I explained what UX is about, and how partner and customers can engage, participate and deploy that Applications UX scientific insight to advantage for their entire business. I also paired up with Oracle Australia in Sydney to visit key customers while there, and back at Oracle in Melbourne I spoke with sales consultants and account managers about regional opportunities and UX strategy, and came away with an understanding of what makes the Oracle market tick in Australia. Mobile worker solution development and user experience is hot news in Australia, and this was a great opportunity to team up with Chris Muir and show how the alignment of the twin stars of UX design patterns and ADF technology enables developers to make great-looking, usable apps that really sparkle. Our UX design patterns--or functional (UI) patterns, to use the developer world language--means that developers now have not only a great tool set to build apps on Oracle ADF/FMW but proven, tested usability solutions to solve common problems they can apply in the IDE too. In all, a whirlwind UX visit, packed with events and delivery opportunities, and all too short a time in the wonderful city of Melbourne. I need to get back there soon! For those who need a reminder, there's a website explaining how to get involved with, and participate in, Applications User Experience (including the Oracle Usability Advisory Board) events and programs. Thank you to AUSOUG, Quest, InSync, Callista, Park Lane IT, everyone at Oracle Australia, Chris Muir, and all the other people who came together to make this a productive visit. Stay tuned for more UX developments and engagements in the region on the Oracle VoX blog and Usable Apps website too!

    Read the article

< Previous Page | 8 9 10 11 12 13 14 15 16  | Next Page >