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• Fixed point math in c#?

  - by x4000

  Hi there, I was wondering if anyone here knows of any good resources for fixed point math in c#? I've seen things like this (http://2ddev.72dpiarmy.com/viewtopic.php?id=156) and this (http://stackoverflow.com/questions/79677/whats-the-best-way-to-do-fixed-point-math), and a number of discussions about whether decimal is really fixed point or actually floating point (update: responders have confirmed that it's definitely floating point), but I haven't seen a solid C# library for things like calculating cosine and sine. My needs are simple -- I need the basic operators, plus cosine, sine, arctan2, PI... I think that's about it. Maybe sqrt. I'm programming a 2D RTS game, which I have largely working, but the unit movement when using floating-point math (doubles) has very small inaccuracies over time (10-30 minutes) across multiple machines, leading to desyncs. This is presently only between a 32 bit OS and a 64 bit OS, all the 32 bit machines seem to stay in sync without issue, which is what makes me think this is a floating point issue. I was aware from this as a possible issue from the outset, and so have limited my use of non-integer position math as much as possible, but for smooth diagonal movement at varying speeds I'm calculating the angle between points in radians, then getting the x and y components of movement with sin and cos. That's the main issue. I'm also doing some calculations for line segment intersections, line-circle intersections, circle-rect intersections, etc, that also probably need to move from floating-point to fixed-point to avoid cross-machine issues. If there's something open source in Java or VB or another comparable language, I could probably convert the code for my uses. The main priority for me is accuracy, although I'd like as little speed loss over present performance as possible. This whole fixed point math thing is very new to me, and I'm surprised by how little practical information on it there is on google -- most stuff seems to be either theory or dense C++ header files. Anything you could do to point me in the right direction is much appreciated; if I can get this working, I plan to open-source the math functions I put together so that there will be a resource for other C# programmers out there. UPDATE: I could definitely make a cosine/sine lookup table work for my purposes, but I don't think that would work for arctan2, since I'd need to generate a table with about 64,000x64,000 entries (yikes). If you know any programmatic explanations of efficient ways to calculate things like arctan2, that would be awesome. My math background is all right, but the advanced formulas and traditional math notation are very difficult for me to translate into code.

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• Access Database using do.cmd openform where clasue - returning all values

  - by primus285

  DoCmd.OpenForm "Database Search", acFormDS, , srcLastName & "AND " & srcFirstName This is only a small sample of the where clause - there are many more terms. First, there is a set of If, Then type tings up top that set the variable srcLastName and srcFirstName to some value. These are not the problem and work just fine. The trouble is getting them to return all values (for instance if you only want to search by one, on neither(return full database list)) Thus far I have settled for (in the if then section): srcLastName = "[Lastname] =" & Chr(34) & cboLastName & Chr(34) - to search for something and srcLastName = "[Lastname] <" & Chr(34) & "Nuthin" & Chr(34) - to return everything (not equal to an absurd and mispelled database term.) The trouble is that data that is null is also not returned. If I have a null firstname, it will not show up in any search period. is there a term I can set [lastname] and [firstname] equal to that will return EVERYTHING (null, open, data, numbers, wierd stuff and otherwise) in a search an SQL form of "give me everything shes got scotty" if you will. the real issue here comes from the data entry - if I could just know that the people would enter everything 100% of the time, this code would work. but forget to enter the persons age or whatever, and it wont return that entry. So far, the only other solution I have come up with is to put a counter in each if then statement. The count will go up by one for each thing that is being searched by. Then if the count is = 1, then I can search by something like just DoCmd.OpenForm "Database Search", acFormDS, , srcLastName or DoCmd.OpenForm "Database Search", acFormDS, , srcFirstName then revert back to the DoCmd.OpenForm "Database Search", acFormDS, , srcLastName & "AND " & srcFirstName when the count is 2 or more truoble here is that it only works for one (unless I so wanted to create a custon list of 2 combined, 3 combined, 4 combined, but that is not happening)

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• The most efficient method of drawing multiple quads in OpenGL

  - by CPatton

  I'm not very keen with OpenGL and I was wondering if someone could give me some insight on this. I'm a 'seasoned' programmer, I've read the redbook about VBOs and the like, but I was wondering from a more experienced person about the best/most efficient way of achieving this. I've been producing this 2d tile-based game engine to be used in several projects. I have a class called "ScreenObject" which is mainly composed of a Dictionary<Point, Tile> The Point key is to show where to render the Tile on the screen, and the Tile contains one or more textures to be drawn at that point. This ScreenObject is where the tiles will be modified, deleted, added, etc.. My original method of drawing the tiles in the testing I've done was to iterate through the ScreenObject and draw each quad at each location separately. From what I've read, this is a massive waste of resources. It wasn't horribly slow in the testing, but after I've completed the animation classes and effect classes, I'm sure it would be extremely slow. And one last thing, if you wouldn't mind.. As I said before, the Tile class can contain multiple textures to be drawn at the Point location on the screen. I recognize possibly two options for me here. Either add a quad at that location for each texture to be drawn, or, somehow.. use a multiple texture for the same quad (if it's possible). Even if each tile contained one texture only, that would be 64 quads to be drawn on the screen. Most of the tiles will contain 2-5 textures, so the number of total quads would increase dramatically with this method. Would it be feasible to add a quad for each new texture, or am I ignoring a better way to do this? Just need some help understanding this if you don't mind :) I've tried to be as concise as possible, and I'd greatly appreciate any responses.. and even some criticism. Programming is often a learning process and one who develops seems to never stops learning. Thanks for your time.

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• Jquery Tools Overlay call on javascript function

  - by user342944

  Hi Guys, I have a jquery overlay window in my html alongwith a button to activate here is the code. <!-- Validation Overlay Box --> <div class="modal" id="yesno" style="top: 100px; left: 320px; position: relative; display: none; z-index: 0; margin-top: 100px;"> <h2> &nbsp;&nbsp;Authentication Failed</h2> <p style="font-family:Arial; font-size:small; text-align:center"> Ether your username or password has been entered incorrectly. Please make sure that your username or password entered correctly... </p> <!-- yes/no buttons --> <p align="center"> <button class="close"> OK </button> </p> </div> Here is the Jquery tools Script <SCRIPT> $(document).ready(function() { var triggers = $(".modalInput").overlay({ // some mask tweaks suitable for modal dialogs mask: { color: '#a2a2a2', loadSpeed: 200, opacity: 0.9 }, closeOnClick: false }); var buttons = $("#yesno button").click(function(e) { // get user input var yes = buttons.index(this) === 0; // do something with the answer triggers.eq(0).html("You clicked " + (yes ? "yes" : "no")); }); $("#prompt form").submit(function(e) { // close the overlay triggers.eq(1).overlay().close(); // get user input var input = $("input", this).val(); // do something with the answer triggers.eq(1).html(input); // do not submit the form return e.preventDefault(); }); }); And here how its called upon clicking on a button or a hyperlink "<BUTTON class="modalInput" rel="#yesno">You clicked no</BUTTON>" All i want is I dont want to show the overlay on clicking on button or through a link. Is it possible to call it through a javascript function like "showOverlay()" ??

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• Creating meaningful routes in wizard style ASP.NET MVC form

  - by R0MANARMY

  I apologize in advance for a long question, figured better have a bit more information than not enough. I'm working on an application with a fairly complex form (~100 fields on it). In order to make the UI a little more presentable the fields are organized into regions and split across multiple (~10) tabs (not unlike this, but each tab does a submit/redirect to next tab). This large input form can also be in one of 3 views (read only, editable, print friendly). The form represents a large domain object (let's call it Foo). I have a controller for said domain object (FooController). It makes sense to me to have the controller be responsible for all the CRUD related operations. Here are the problems I'm having trouble figuring out. Goals: I'd like to keep to conventions so that Foo/Create creates a new record Foo/Delete deletes a record Foo/Edit/{foo_id} takes you to the first tab of the form ...etc I'd like to be able to not repeat the data access code such that I can have Foo/Edit/{foo_id}/tab1 Foo/View/{foo_id}/tab1 Foo/Print/{foo_id}tab1 ...etc use the same data access code to get the data and just specify which view to use to render it. My current implementation has a massive FooController with Create, Delete, Tab1, Tab2, etc actions. Tab actions are split out into separate files for organization (using partial classes, which may or may not be abuse of partial classes). Problem I'm running into is how to organize my controller(s) and routes to make that happen. I have the default route {controller}/{action}/{id} Which handles goal 1 properly but doesn't quite play nice with goal 2. I tried to address goal 2 by defining extra routes like so: routes.MapRoute( "FooEdit", "Foo/Edit/{id}/{action}", new { controller = "Foo", action = "Tab1", mode = "Edit", id = (string)null } ); routes.MapRoute( "FooView", "Foo/View/{id}/{action}", new { controller = "Foo", action = "Tab1", mode = "View", id = (string)null } ); routes.MapRoute( "FooPrint", "Foo/Print/{id}/{action}", new { controller = "Foo", action = "Tab1", mode = "Print", id = (string)null } ); However defining these extra routes causes the Url.Action to generate routs like Foo/Edit/Create instead of Foo/Create. That leads me to believe I designed something very very wrong, but this is my first attempt an asp.net mvc project and I don't know any better. Any advice with this particular situation would be awesome, but feedback on design in similar projects is welcome.

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• Looking for efficient scaling patterns for Silverlight application with distributed text-file data s

  - by Edward Tanguay

  I'm designing a Silverlight software solution for students and teachers to record flashcards, e.g. words and phrases that students find while reading and errors that teachers notice while teaching. Requirements are: each person publishes his own flashcards in a file on a web server, e.g. http://:www.mywebserver.com/flashcards.txt other people subscribe to that person's flashcards by using a Silverlight flashcard reader that I have developed and entering the URLs of flashcard files they want to subscribe to, URLs and imported flashcards being saved in IsolatedStorage the flashcards.txt file has the following simple format: title, then blocks of question/answers: Jim Smith's flashcards from English class 53-222, winter semester 2009 ==fla Das kann nicht sein. That can't be. ==fla Es sei denn, er kommt nicht. Unless he doesn't come. The user then makes public the URL to his flashcard file and other readers begin reading in his flashcards. In order to lower the bar for non-technical users to contribute, it will even be possible for them to save this text in a Google Document, which they publish and distribute the URL. The flashcard readers will then recognize it is a google document and perform the necessary screen scraping to get at the raw text. I have two technical questions about this approach: What is a best way to plan now for scalability issues: e.g. if your reader is subscribed to 10 flashcard files that are each 200K, it will have to download 2MB of text just to find out if any new flashcards are available. Or can I somehow accurately and consistently get at the last update date/time of text files on servers and published google docs? Each reader will have the ability to allow the person to test himself on imported flashcards and add meta information to them, e.g. categorize them, edit them, etc. This information will be stored in IsolatedStorage along with the important flashcards themselves. What is a good pattern to allow these readers to share and synchronize this meta data, e.g. so when you are looking at a flashcard you can see that 5 other people have made corrections to it. The best solution I can think of now is that the Silverlight readers will have to republish their data to a central database, but then there is the problem of uniquely identifying each flashcard, the best approach seems to be URL + position-in-file, or even better URL + original text of both question and answer fields, but both of these have their obvious drawbacks. The main requirement is that the bar for participation is kept as low as possible, i.e. type text in a google document, publish it, distribute the URL, and you're publishing within the flashcard community. So I want to come up with the most efficient technical solutions in order to compensate for the lack of database, lack of unique ids, etc. For those who have designed or developed similar non-traditional, distributed database projects like this, what advice, experience or best-practice tips you can share on the above two points?

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• mysql index optimization for a table with multiple indexes that index some of the same columns

  - by Sean

  I have a table that stores some basic data about visitor sessions on third party web sites. This is its structure: id, site_id, unixtime, unixtime_last, ip_address, uid There are four indexes: id, site_id/unixtime, site_id/ip_address, and site_id/uid There are many different types of ways that we query this table, and all of them are specific to the site_id. The index with unixtime is used to display the list of visitors for a given date or time range. The other two are used to find all visits from an IP address or a "uid" (a unique cookie value created for each visitor), as well as determining if this is a new visitor or a returning visitor. Obviously storing site_id inside 3 indexes is inefficient for both write speed and storage, but I see no way around it, since I need to be able to quickly query this data for a given specific site_id. Any ideas on making this more efficient? I don't really understand B-trees besides some very basic stuff, but it's more efficient to have the left-most column of an index be the one with the least variance - correct? Because I considered having the site_id being the second column of the index for both ip_address and uid but I think that would make the index less efficient since the IP and UID are going to vary more than the site ID will, because we only have about 8000 unique sites per database server, but millions of unique visitors across all ~8000 sites on a daily basis. I've also considered removing site_id from the IP and UID indexes completely, since the chances of the same visitor going to multiple sites that share the same database server are quite small, but in cases where this does happen, I fear it could be quite slow to determine if this is a new visitor to this site_id or not. The query would be something like: select id from sessions where uid = 'value' and site_id = 123 limit 1 ... so if this visitor had visited this site before, it would only need to find one row with this site_id before it stopped. This wouldn't be super fast necessarily, but acceptably fast. But say we have a site that gets 500,000 visitors a day, and a particular visitor loves this site and goes there 10 times a day. Now they happen to hit another site on the same database server for the first time. The above query could take quite a long time to search through all of the potentially thousands of rows for this UID, scattered all over the disk, since it wouldn't be finding one for this site ID. Any insight on making this as efficient as possible would be appreciated :) Update - this is a MyISAM table with MySQL 5.0. My concerns are both with performance as well as storage space. This table is both read and write heavy. If I had to choose between performance and storage, my biggest concern is performance - but both are important. We use memcached heavily in all areas of our service, but that's not an excuse to not care about the database design. I want the database to be as efficient as possible.

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• CodeGolf: Brothers

  - by John McClane

  Hi guys, I just finished participating in the 2009 ACM ICPC Programming Conest in the Latinamerican Finals. These questions were for Brazil, Bolivia, Chile, etc. My team and I could only finish two questions out of the eleven (not bad I think for the first try). Here's one we could finish. I'm curious to seeing any variations to the code. The question in full: ps: These questions can also be found on the official ICPC website available to everyone. In the land of ACM ruled a greeat king who became obsessed with order. The kingdom had a rectangular form, and the king divided the territory into a grid of small rectangular counties. Before dying the king distributed the counties among his sons. The king was unaware of the rivalries between his sons: The first heir hated the second but not the rest, the second hated the third but not the rest, and so on...Finally, the last heir hated the first heir, but not the other heirs. As soon as the king died, the strange rivaly among the King's sons sparked off a generalized war in the kingdom. Attacks only took place between pairs of adjacent counties (adjacent counties are those that share one vertical or horizontal border). A county X attacked an adjacent county Y whenever X hated Y. The attacked county was always conquered. All attacks where carried out simultanously and a set of simultanous attacks was called a battle. After a certain number of battles, the surviving sons made a truce and never battled again. For example if the king had three sons, named 0, 1 and 2, the figure below shows what happens in the first battle for a given initial land distribution: INPUT The input contains several test cases. The first line of a test case contains four integers, N, R, C and K. N - The number of heirs (2 <= N <= 100) R and C - The dimensions of the land. (2 <= R,C <= 100) K - Number of battles that are going to take place. (1 <= K <= 100) Heirs are identified by sequential integers starting from zero. Each of the next R lines contains C integers HeirIdentificationNumber (saying what heir owns this land) separated by single spaces. This is to layout the initial land. The last test case is a line separated by four zeroes separated by single spaces. (To exit the program so to speak) Output For each test case your program must print R lines with C integers each, separated by single spaces in the same format as the input, representing the land distribution after all battles. Sample Input: Sample Output: 3 4 4 3 2 2 2 0 0 1 2 0 2 1 0 1 1 0 2 0 2 2 2 0 0 1 2 0 0 2 0 0 0 1 2 2 Another example: Sample Input: Sample Output: 4 2 3 4 1 0 3 1 0 3 2 1 2 2 1 2

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• Install Trac on 64bits Windows 7

  - by Tufo

  I'm configuring a new Developing Server that came with Windows 7 64bits. It must have installed Trac with Subversion integration. I install Subversion with VisualSVN 2.1.1, clients with TortoiseSVN 1.6.7 and AnkhSVN 2.1.7 for Visual Studio 2008 SP1 integration. All works fine! my problem begun when going to Trac installation. I install python 2.6 all fine. Trac hasn't a x64 windows installer, so I installed it manually by compiling it with python console (C:\Python26\python.exe C:/TRAC/setup.py install). After that, I can create TRAC projects normally, the Trac core is working fine. And so the problem begins, lets take a look at the Trac INSTALL file: Requirements To install Trac, the following software packages must be installed: Python, version = 2.3. Subversion, version = 1.0. (= 1.1.xrecommended) Subversion SWIG Python bindings (not PySVN). PySQLite,version 1.x (for SQLite 2.x) or version 2.x (for SQLite 3.x) Clearsilver, version = 0.9.3 (0.9.14 recommended) Python: OK Subverion: OK Subversion SWIG Python bindings (not PySVN): Here I face the first issue, he asks me for 'cd' to the swig directory and run the 'configure' file, and the result is: C:\swigwin-1.3.40> c:\python26\python.exe configure File "configure", line 16 DUALCASE=1; export DUALCASE # for MKS sh ^ SyntaxError: invalid syntax PySQLite, version 1.x (for SQLite 2.x) or version 2.x (for SQLite 3.x): Don't need, as Python 2.6 comes with SQLLite Clearsilver, version = 0.9.3 (0.9.14 recommended): Second issue, Clearsilver only has 32bit installer wich does not recognize python installation (as registry keys are in different places from 32 to 64 bits). So I try to manually install it with python console. It returns me a error of the same kind as SWIG: C:\clearsilver-0.10.5>C:\python26\python.exe ./configure File "./configure", line 13 if test -n "${ZSH_VERSION+set}" && (emulate sh) >/dev/null 2>&1; then ^ SyntaxError: invalid syntax When I simulate a web server using the "TRACD" command, it runs fine when I disable svn support but when I try to open the web page it shows me a error regarding ClearSilver is not installed for generating the html content. AND (for making me more happy) This TRAC will run over IIS7, I mustn't install Apache... I'm nearly crazy with this issue... HELP!!!

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• VS2008 C++ MFC Access Violation ONLY when stepping through debug mode

  - by HotOil

  Hi. This is crazy. It started happening in my main project, so I created a tiny sample brand-new project to reproduce it in and sure enough.. It does NOT happen in a sample project I created that is only a Win32 console app. I'm running this on Win7x64, if that matters. VS2008 SP1. Here goes. I create a small dialog app with a button. Put a breakpoint in the handler function for that button. The button handler function looks like this: void CTestProjectDlg::OnBnClickedButton1() { int i=2; m_csHello.Format(_T("Hello World!")); << breakpoint here UpdateData(FALSE); } Click the button, hit the breakpoint. F10 to step, and boom: "First-chance exception at 0x0398f77b in TestProject.exe: 0xC0000005: Access violation." It gives me the option to Break or Continue. If I Continue, it just hits it again, only not "First Chance". Yes I have that exception checked in the Debug-Exceptions dlg. If I Break, the call stack just shows me the line where the breakpoint is. If I F10 again.. I get the exception again, only now the callstack shows me in the _AfxDispatchCmdMsg() function, and my original OnBnClickedButton1() is not in the callstack anymore. It doesn't matter where I put the breakpoint. If, instead of F10, I just continue with F5, it works normally. Now.. if I build a Release version and run in debugging mode: I hit the breakpoint, and all the pointers, variable values look normal. F10, and these turn to garbage. The this pointer is now zero. The m_csHello is now However, in Release mode, an exception is not caught, and it all runs fine. The "hello World string gets displayed in the dialog box as it should. I have put in an inquiry to see if some patch was installed on my box by the IT dept in the last day or two. This wasn't happening 2 days ago. What do you think? Is VS2008 corrupted? Thanks.

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• In MySQL, what is the most effective query design for joining large tables with many to many relatio

  - by lighthouse65

  In our application, we collect data on automotive engine performance -- basically source data on engine performance based on the engine type, the vehicle running it and the engine design. Currently, the basis for new row inserts is an engine on-off period; we monitor performance variables based on a change in engine state from active to inactive and vice versa. The related engineState table looks like this: +---------+-----------+---------------+---------------------+---------------------+-----------------+ | vehicle | engine | engine_state | state_start_time | state_end_time | engine_variable | +---------+-----------+---------------+---------------------+---------------------+-----------------+ | 080025 | E01 | active | 2008-01-24 16:19:15 | 2008-01-24 16:24:45 | 720 | | 080028 | E02 | inactive | 2008-01-24 16:19:25 | 2008-01-24 16:22:17 | 304 | +---------+-----------+---------------+---------------------+---------------------+-----------------+ For a specific analysis, we would like to analyze table content based on a row granularity of minutes, rather than the current basis of active / inactive engine state. For this, we are thinking of creating a simple productionMinute table with a row for each minute in the period we are analyzing and joining the productionMinute and engineEvent tables on the date-time columns in each table. So if our period of analysis is from 2009-12-01 to 2010-02-28, we would create a new table with 129,600 rows, one for each minute of each day for that three-month period. The first few rows of the productionMinute table: +---------------------+ | production_minute | +---------------------+ | 2009-12-01 00:00 | | 2009-12-01 00:01 | | 2009-12-01 00:02 | | 2009-12-01 00:03 | +---------------------+ The join between the tables would be engineState AS es LEFT JOIN productionMinute AS pm ON es.state_start_time <= pm.production_minute AND pm.production_minute <= es.event_end_time. This join, however, brings up multiple environmental issues: The engineState table has 5 million rows and the productionMinute table has 130,000 rows When an engineState row spans more than one minute (i.e. the difference between es.state_start_time and es.state_end_time is greater than one minute), as is the case in the example above, there are multiple productionMinute table rows that join to a single engineState table row When there is more than one engine in operation during any given minute, also as per the example above, multiple engineState table rows join to a single productionMinute row In testing our logic and using only a small table extract (one day rather than 3 months, for the productionMinute table) the query takes over an hour to generate. In researching this item in order to improve performance so that it would be feasible to query three months of data, our thoughts were to create a temporary table from the engineEvent one, eliminating any table data that is not critical for the analysis, and joining the temporary table to the productionMinute table. We are also planning on experimenting with different joins -- specifically an inner join -- to see if that would improve performance. What is the best query design for joining tables with the many:many relationship between the join predicates as outlined above? What is the best join type (left / right, inner)?

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• Faster Matrix Multiplication in C#

  - by Kyle Lahnakoski

  I have as small c# project that involves matrices. I am processing large amounts of data by splitting it into n-length chunks, treating the chucks as vectors, and multiplying by a Vandermonde** matrix. The problem is, depending on the conditions, the size of the chucks and corresponding Vandermonde** matrix can vary. I have a general solution which is easy to read, but way too slow: public byte[] addBlockRedundancy(byte[] data) { if (data.Length!=numGood) D.error("Expecting data to be just "+numGood+" bytes long"); aMatrix d=aMatrix.newColumnMatrix(this.mod, data); var r=vandermonde.multiplyBy(d); return r.ToByteArray(); }//method This can process about 1/4 megabytes per second on my i5 U470 @ 1.33GHz. I can make this faster by manually inlining the matrix multiplication: int o=0; int d=0; for (d=0; d<data.Length-numGood; d+=numGood) { for (int r=0; r<numGood+numRedundant; r++) { Byte value=0; for (int c=0; c<numGood; c++) { value=mod.Add(value, mod.Multiply(vandermonde.get(r, c), data[d+c])); }//for output[r][o]=value; }//for o++; }//for This can process about 1 meg a second. (Please note the "mod" is performing operations over GF(2^8) modulo my favorite irreducible polynomial.) I know this can get a lot faster: After all, the Vandermonde** matrix is mostly zeros. I should be able to make a routine, or find a routine, that can take my matrix and return a optimized method which will effectively multiply vectors by the given matrix, but faster. Then, when I give this routine a 5x5 Vandermonde matrix (the identity matrix), there is simply no arithmetic to perform, and the original data is just copied. ** Please note: What I use the term "Vandermonde", I actually mean an Identity matrix with some number of rows from the Vandermonde matrix appended (see comments). This matrix is wonderful because of all the zeros, and because if you remove enough rows (of your choosing) to make it square, it is an invertible matrix. And, of course, I would like to use this same routine to convert any one of those inverted matrices into an optimized series of instructions. How can I make this matrix multiplication faster? Thanks! (edited to correct my mistake with Vandermonde matrix)

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• Winform radiobutton data binding

  - by Rajarshi

  I am following the "Presentation Model" design pattern suggested by Martin Fowler for my GUI architecture in a Windows Forms project. "The essence of a Presentation Model is of a fully self-contained class that represents all the data and behavior of the UI window, but without any of the controls used to render that UI on the screen. A view then simply projects the state of the presentation model onto the glass...." - Martin Fowler Read more about this pattern at www.martinfowler.com/eaaDev/PresentationModel.html I am finding the concept very fluid and easy to understand except this one issue of data binding RadioButtons to properties on the Data/Domain object. Suposing I have a Windows Form with 3 radio buttons to depict some "Mode" options as - Auto Manual Import How can I use boolean properties on Data/Domain Objects to DataBind to these buttons? I have tried many ways but to no avail. For example I would like to code like - rbtnAutoMode.DataBindings.Add("Text", myBusinessObject, "IsAutoMode"); rbtnManualMode.DataBindings.Add("Text", myBusinessObject, "IsManualMode"); rbtnImportMode.DataBindings.Add("Text", myBusinessObject, "IsImportMode"); There should be a fourth property like "SelectedMode" on the data/domain object which at the end should depict a single value like "SelectedMode = Auto". I am trying to update this property when any of the "IsAutoMode", "IsManualMode" or "IsImportMode" is changed, e.g. through the property setters. I have INotifyPropertyChanged implemented on my data/domain object so, updating any data/domain object property automatically updates my UI controls, that's not an issue. There is a good example of binding 2 radio buttons here - http://stackoverflow.com/questions/344964/how-do-i-use-databinding-with-windows-forms-radio-buttons but I am missing the link while implementing the same with 3 buttons. I am having very erratic behaviors for the Radio Buttons. I hope I was able to explain reasonably. I am actually in a hurry and could not put a detailed code on post, but any help in this regard is appreciated. There is a simple solution to this issue by exposing a method like - public void SetMode(Modes mode) { this._selectedMode = mode; } which could be called from the "CheckedChanged" event of the Radio Buttons from the UI and would perfectly set the "SelectedMode" on the business object, but I need to stretch the limits to verify whether this can be done by DataBinding.

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• Correlated SQL Join Query from multiple tables

  - by SooDesuNe

  I have two tables like the ones below. I need to find what exchangeRate was in effect at the dateOfPurchase. I've tried some correlated sub queries, but I'm having difficulty getting the correlated record to be used in the sub queries. I expect a solution will need to follow this basic outline: SELECT only the exchangeRates for the applicable countryCode From 1. SELECT the newest exchangeRate less than the dateOfPurchase Fill in the query table with all the fields from 2. and the purchasesTable. My Tables: purchasesTable: > dateOfPurchase | costOfPurchase | countryOfPurchase > 29-March-2010 | 20.00 | EUR > 29-March-2010 | 3000 | JPN > 30-March-2010 | 50.00 | EUR > 30-March-2010 | 3000 | JPN > 30-March-2010 | 2000 | JPN > 31-March-2010 | 100.00 | EUR > 31-March-2010 | 125.00 | EUR > 31-March-2010 | 2000 | JPN > 31-March-2010 | 2400 | JPN costOfPurchase is in whatever the local currency is for a given countryCode exchangeRateTable > effectiveDate | countryCode | exchangeRate > 29-March-2010 | JPN | 90 > 29-March-2010 | EUR | 1.75 > 30-March-2010 | JPN | 92 > 31-March-2010 | JPN | 91 The results of the query that I'm looking for: > dateOfPurchase | costOfPurchase | countryOfPurchase | exchangeRate > 29-March-2010 | 20.00 | EUR | 1.75 > 29-March-2010 | 3000 | JPN | 90 > 30-March-2010 | 50.00 | EUR | 1.75 > 30-March-2010 | 3000 | JPN | 92 > 30-March-2010 | 2000 | JPN | 92 > 31-March-2010 | 100.00 | EUR | 1.75 > 31-March-2010 | 125.00 | EUR | 1.75 > 31-March-2010 | 2000 | JPN | 91 > 31-March-2010 | 2400 | JPN | 91 So for example in the results, the exchange rate, in effect for EUR on 31-March was 1.75. I'm using Access, but a MySQL answer would be fine too. UPDATE: Modification to Allan's answer: SELECT dateOfPurchase, costOfPurchase, countryOfPurchase, exchangeRate FROM purchasesTable p LEFT OUTER JOIN (SELECT e1.exchangeRate, e1.countryCode, e1.effectiveDate, min(e2.effectiveDate) AS enddate FROM exchangeRateTable e1 LEFT OUTER JOIN exchangeRateTable e2 ON e1.effectiveDate < e2.effectiveDate AND e1.countryCode = e2.countryCode GROUP BY e1.exchangeRate, e1.countryCode, e1.effectiveDate) e ON p.dateOfPurchase >= e.effectiveDate AND (p.dateOfPurchase < e.enddate OR e.enddate is null) AND p.countryOfPurchase = e.countryCode I had to make a couple small changes.

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• Event Listener in Google Charts API

  - by DeanGrobler

  I'm busy using Google Charts in one of my projects to display data in a table. Everything is working great. Except that I need to see what line a user selected once they click a button. This would obviously be done with Javascript, but I've been struggling for days now to no avail. Below I've pasted code for a simple example of the table, and the Javascript function that I want to use (that doesn't work). <html> <head> <script type='text/javascript' src='https://www.google.com/jsapi'></script> <script type='text/javascript'> google.load('visualization', '1', {packages:['table']}); google.setOnLoadCallback(drawTable); var table = ""; function drawTable() { var data = new google.visualization.DataTable(); data.addColumn('string', 'Name'); data.addColumn('number', 'Salary'); data.addColumn('boolean', 'Full Time Employee'); data.addRows(4); data.setCell(0, 0, 'Mike'); data.setCell(0, 1, 10000, '$10,000'); data.setCell(0, 2, true); data.setCell(1, 0, 'Jim'); data.setCell(1, 1, 8000, '$8,000'); data.setCell(1, 2, false); data.setCell(2, 0, 'Alice'); data.setCell(2, 1, 12500, '$12,500'); data.setCell(2, 2, true); data.setCell(3, 0, 'Bob'); data.setCell(3, 1, 7000, '$7,000'); data.setCell(3, 2, true); table = new google.visualization.Table(document.getElementById('table_div')); table.draw(data, {showRowNumber: true}); } function selectionHandler() { selectedData = table.getSelection(); row = selectedData[0].row; item = table.getValue(row,0); alert("You selected :" + item); } </script> </head> <body> <div id='table_div'></div> <input type="button" value="Select" onClick="selectionHandler()"> </body> </html> Thanks in advance for anyone taking the time to look at this. I've honestly tried my best with this, hope someone out there can help me out a bit.

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• Why is numpy's einsum faster than numpy's built in functions?

  - by Ophion

  Lets start with three arrays of dtype=np.double. Timings are performed on a intel CPU using numpy 1.7.1 compiled with icc and linked to intel's mkl. A AMD cpu with numpy 1.6.1 compiled with gcc without mkl was also used to verify the timings. Please note the timings scale nearly linearly with system size and are not due to the small overhead incurred in the numpy functions if statements these difference will show up in microseconds not milliseconds: arr_1D=np.arange(500,dtype=np.double) large_arr_1D=np.arange(100000,dtype=np.double) arr_2D=np.arange(500**2,dtype=np.double).reshape(500,500) arr_3D=np.arange(500**3,dtype=np.double).reshape(500,500,500) First lets look at the np.sum function: np.all(np.sum(arr_3D)==np.einsum('ijk->',arr_3D)) True %timeit np.sum(arr_3D) 10 loops, best of 3: 142 ms per loop %timeit np.einsum('ijk->', arr_3D) 10 loops, best of 3: 70.2 ms per loop Powers: np.allclose(arr_3D*arr_3D*arr_3D,np.einsum('ijk,ijk,ijk->ijk',arr_3D,arr_3D,arr_3D)) True %timeit arr_3D*arr_3D*arr_3D 1 loops, best of 3: 1.32 s per loop %timeit np.einsum('ijk,ijk,ijk->ijk', arr_3D, arr_3D, arr_3D) 1 loops, best of 3: 694 ms per loop Outer product: np.all(np.outer(arr_1D,arr_1D)==np.einsum('i,k->ik',arr_1D,arr_1D)) True %timeit np.outer(arr_1D, arr_1D) 1000 loops, best of 3: 411 us per loop %timeit np.einsum('i,k->ik', arr_1D, arr_1D) 1000 loops, best of 3: 245 us per loop All of the above are twice as fast with np.einsum. These should be apples to apples comparisons as everything is specifically of dtype=np.double. I would expect the speed up in an operation like this: np.allclose(np.sum(arr_2D*arr_3D),np.einsum('ij,oij->',arr_2D,arr_3D)) True %timeit np.sum(arr_2D*arr_3D) 1 loops, best of 3: 813 ms per loop %timeit np.einsum('ij,oij->', arr_2D, arr_3D) 10 loops, best of 3: 85.1 ms per loop Einsum seems to be at least twice as fast for np.inner, np.outer, np.kron, and np.sum regardless of axes selection. The primary exception being np.dot as it calls DGEMM from a BLAS library. So why is np.einsum faster that other numpy functions that are equivalent? The DGEMM case for completeness: np.allclose(np.dot(arr_2D,arr_2D),np.einsum('ij,jk',arr_2D,arr_2D)) True %timeit np.einsum('ij,jk',arr_2D,arr_2D) 10 loops, best of 3: 56.1 ms per loop %timeit np.dot(arr_2D,arr_2D) 100 loops, best of 3: 5.17 ms per loop The leading theory is from @sebergs comment that np.einsum can make use of SSE2, but numpy's ufuncs will not until numpy 1.8 (see the change log). I believe this is the correct answer, but have not been able to confirm it. Some limited proof can be found by changing the dtype of input array and observing speed difference and the fact that not everyone observes the same trends in timings.

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• Scipy Negative Distance? What?

  - by disappearedng

  I have a input file which are all floating point numbers to 4 decimal place. i.e. 13359 0.0000 0.0000 0.0001 0.0001 0.0002` 0.0003 0.0007 ... (the first is the id). My class uses the loadVectorsFromFile method which multiplies it by 10000 and then int() these numbers. On top of that, I also loop through each vector to ensure that there are no negative values inside. However, when I perform _hclustering, I am continually seeing the error, "Linkage Z contains negative values". I seriously think this is a bug because: I checked my values, the values are no where small enough or big enough to approach the limits of the floating point numbers and the formula that I used to derive the values in the file uses absolute value (my input is DEFINITELY right). Can someone enligten me as to why I am seeing this weird error? What is going on that is causing this negative distance error? ===== def loadVectorsFromFile(self, limit, loc, assertAllPositive=True, inflate=True): """Inflate to prevent "negative" distance, we use 4 decimal points, so *10000 """ vectors = {} self.winfo("Each vector is set to have %d limit in length" % limit) with open( loc ) as inf: for line in filter(None, inf.read().split('\n')): l = line.split('\t') if limit: scores = map(float, l[1:limit+1]) else: scores = map(float, l[1:]) if inflate: vectors[ l[0]] = map( lambda x: int(x*10000), scores) #int might save space else: vectors[ l[0]] = scores if assertAllPositive: #Assert that it has no negative value for dirID, l in vectors.iteritems(): if reduce(operator.or_, map( lambda x: x < 0, l)): self.werror( "Vector %s has negative values!" % dirID) return vectors def main( self, inputDir, outputDir, limit=0, inFname="data.vectors.all", mappingFname='all.id.features.group.intermediate'): """ Loads vector from a file and start clustering INPUT vectors is { featureID: tfidfVector (list), } """ IDFeatureDic = loadIdFeatureGroupDicFromIntermediate( pjoin(self.configDir, mappingFname)) if not os.path.exists(outputDir): os.makedirs(outputDir) vectors = self.loadVectorsFromFile( limit, pjoin( inputDir, inFname)) for threshold in map( lambda x:float(x)/30, range(20,30)): clusters = self._hclustering(threshold, vectors) if clusters: outputLoc = pjoin(outputDir, "threshold.%s.result" % str(threshold)) with open(outputLoc, 'w') as outf: for clusterNo, cluster in clusters.iteritems(): outf.write('%s\n' % str(clusterNo)) for featureID in cluster: feature, group = IDFeatureDic[featureID] outline = "%s\t%s\n" % (feature, group) outf.write(outline.encode('utf-8')) outf.write("\n") else: continue def _hclustering(self, threshold, vectors): """function which you should call to vary the threshold vectors: { featureID: [ tfidf scores, tfidf score, .. ] """ clusters = defaultdict(list) if len(vectors) > 1: try: results = hierarchy.fclusterdata( vectors.values(), threshold, metric='cosine') except ValueError, e: self.werror("_hclustering: %s" % str(e)) return False for i, featureID in enumerate( vectors.keys()):

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• PyGTK: dynamic label wrapping

  - by detly

  It's a known bug/issue that a label in GTK will not dynamically resize when the parent changes. It's one of those really annoying small details, and I want to hack around it if possible. I followed the approach at 16 software, but as per the disclaimer you cannot then resize it smaller. So I attempted a trick mentioned in one of the comments (the set_size_request call in the signal callback), but this results in some sort of infinite loop (try it and see). Does anyone have any other ideas? (You can't block the signal just for the duration of the call, since as the print statements seem to indicate, the problem starts after the function is left.) The code is below. You can see what I mean if you run it and try to resize the window larger and then smaller. (If you want to see the original problem, comment out the line after "Connect to the size-allocate signal", run it, and resize the window bigger.) The Glade file ("example.glade"): <?xml version="1.0"?> <glade-interface> <!-- interface-requires gtk+ 2.16 --> <!-- interface-naming-policy project-wide --> <widget class="GtkWindow" id="window1"> <property name="visible">True</property> <signal name="destroy" handler="on_destroy"/> <child> <widget class="GtkLabel" id="label1"> <property name="visible">True</property> <property name="label" translatable="yes">In publishing and graphic design, lorem ipsum[p][1][2] is the name given to commonly used placeholder text (filler text) to demonstrate the graphic elements of a document or visual presentation, such as font, typography, and layout. The lorem ipsum text, which is typically a nonsensical list of semi-Latin words, is a hacked version of a Latin text by Cicero, with words/letters omitted and others inserted, but not proper Latin[1][2] (see below: History and discovery). The closest English translation would be "pain itself" (dolorem = pain, grief, misery, suffering; ipsum = itself).</property> <property name="wrap">True</property> </widget> </child> </widget> </glade-interface> The Python code: #!/usr/bin/python import pygtk import gobject import gtk.glade def wrapped_label_hack(gtklabel, allocation): print "In wrapped_label_hack" gtklabel.set_size_request(allocation.width, -1) # If you uncomment this, we get INFINITE LOOPING! # gtklabel.set_size_request(-1, -1) print "Leaving wrapped_label_hack" class ExampleGTK: def __init__(self, filename): self.tree = gtk.glade.XML(filename, "window1", "Example") self.id = "window1" self.tree.signal_autoconnect(self) # Connect to the size-allocate signal self.get_widget("label1").connect("size-allocate", wrapped_label_hack) def on_destroy(self, widget): self.close() def get_widget(self, id): return self.tree.get_widget(id) def close(self): window = self.get_widget(self.id) if window is not None: window.destroy() gtk.main_quit() if __name__ == "__main__": window = ExampleGTK("example.glade") gtk.main()

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• Offline backup synchronization

  - by Pavan Kumar

  There is a Central Server running Windows Server 2003 and SQL Server 2005 and there are 7 client machines situated in various places and has XP Pro & SQL Server 2005 installed in all of them. They are not interconnected so they are physically seperate. One person goes to each of these centers maybe twice a month and takes the backup (Full database consisting of mdf and ldf files) with a pen drive and brings it to the Central server which contains the central database holding same schema as all the other client databases. I need to synchronize each backup database (belonging to different centers) one by one to update the existing data or inserting new data in the central database . The solution i got was Replication. The pendrive is brought to central server consisting of 7 instances of the databases and then the databases is attached to the central server one by one to the same SQL Server where the central database exists. Then my idea was to replicate the backup database one by one i.e using single subscription (Central Database) and multiple publication ( i.e 7 instances of databases in my case) toplogy by performing replication locally (i.e in the same machine). So i tried to develop a UI in C# .Net to programatically run the Transactional Replication with push subscription using RMO Programming (which is incomplete as of now because there is no point in developing when you already know it is not the solution). Transactional Replication can either be set to initialize with a snapshot or without a snapshot. If i go for the first option i.e with a snapshot , the data whatever is present in Central Database is overwritten by the new data . So the data present initially in the central database is lost. If i try to initialize without snapshot , no data (the data already has the updated and new data) will be sent from the backup database to server. The replication will work in a scenario where any incremental changes is done only after you set the replication . So the initial data whatever was present in the backup database when setting up the replication will not be replicated when running the snapshot agent for the first time to synchronize. Only changes in the backup database thereafter will be reflected to the central database .(Remember I am not going to insert new data or make any changes to the backup database after i attach it to the Central Server. ) So this solution is not feasible. I want a solution for synchronizing from one client database to central database present in the same machine using C#.NET. If you can provide me small example maybe with two databases(with same schema) DB1(Client) to DB2(Server) consisting of one or two tables it will be very helpful. The synchronization is not bidirectional.I want to only update existing data or insert new data from DB1 to DB2 (DB2 may contain some data initially). Thanks and Regards Pavan

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• VB6 app not executing as scheduled task unless user is logged on

  - by Tedd Hansen

  Hi Would greatly apprechiate some help on this one! It may be a tricky one. :) Problem I have an VB6 application which is set up as scheduled task. It starts every time, but when executing CreateObject it fails if user is not logged on to computer. I am looking for information on what could cause this. Primary suspicion is that some Windows API fails. Key points Behaviour confirmed on Windows 2000, 2003, 2008 and Vista. The application executes as user X at scheduled time, executed by Windows Task Scheduler. It executes every time. Application does start! -- If user X is logged on via RDP it runs perfectly. (Note that user doesn't need to be connected, only logged on) -- If user X is not logged on to computer the application fails. Failure point Application fails when using CreateObject() to instansiate a DCOM object which is also part of the application. The DCOM objects declare .dll-references at startup (globally/on top of .bas-file) and run a small startup function. Failure must be during startup, possibly in one of the .dll-declarations. Thoughts After some Googling my initial suspicion was directed at MAPI. From what I could see MAPI required user to be logged on. The application has MAPI references. But even with all MAPI references removed it still does not work. What is the difference if an user is logged on? Registry mapping? Environment? explorer.exe is running. Isn't the user logged on when application executes as the user? What info would help? A definitive answer would be truly great. Any information regarding any VB6 feature/Windows API that could act differently depending on wether user is logged on or not would definitively help. Similar experiences may lead me in the right direction. Tips on debuggin this. Thanks! :)

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• Most efficient method to query a Young Tableau

  - by Matthieu M.

  A Young Tableau is a 2D matrix A of dimensions M*N such that: i,j in [0,M)x[0,N): for each p in (i,M), A[i,j] <= A[p,j] for each q in (j,N), A[i,j] <= A[i,q] That is, it's sorted row-wise and column-wise. Since it may contain less than M*N numbers, the bottom-right values might be represented either as missing or using (in algorithm theory) infinity to denote their absence. Now the (elementary) question: how to check if a given number is contained in the Young Tableau ? Well, it's trivial to produce an algorithm in O(M*N) time of course, but what's interesting is that it is very easy to provide an algorithm in O(M+N) time: Bottom-Left search: Let x be the number we look for, initialize i,j as M-1, 0 (bottom left corner) If x == A[i,j], return true If x < A[i,j], then if i is 0, return false else decrement i and go to 2. Else, if j is N-1, return false else increment j This algorithm does not make more than M+N moves. The correctness is left as an exercise. It is possible though to obtain a better asymptotic runtime. Pivot Search: Let x be the number we look for, initialize i,j as floor(M/2), floor(N/2) If x == A[i,j], return true If x < A[i,j], search (recursively) in A[0:i-1, 0:j-1], A[i:M-1, 0:j-1] and A[0:i-1, j:N-1] Else search (recursively) in A[i+1:M-1, 0:j], A[i+1:M-1, j+1:N-1] and A[0:i, j+1:N-1] This algorithm proceed by discarding one of the 4 quadrants at each iteration and running recursively on the 3 left (divide and conquer), the master theorem yields a complexity of O((N+M)**(log 3 / log 4)) which is better asymptotically. However, this is only a big-O estimation... So, here are the questions: Do you know (or can think of) an algorithm with a better asymptotical runtime ? Like introsort prove, sometimes it's worth switching algorithms depending on the input size or input topology... do you think it would be possible here ? For 2., I am notably thinking that for small size inputs, the bottom-left search should be faster because of its O(1) space requirement / lower constant term.

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• Which third party website thumbnailing services do you use?

  - by Ben Delarre

  I've got a requirement for showing thumbnails of arbitrary websites. I need to be able to show small thumbnails (120px by 90px), and larger thumbnails of around 480px wide. I'll need to specify the queue and invalid placeholder images and preferably have a pingback when the queued images are processed so I can respond appropriately. I'd also need a simple API I can use either directly embedded in my HTML, or from a simple web request to queue the images. I've been looking at various services ranging from low-fi services, to large scale ones - here's some examples: www.bitpixels.com Uses Google AppEngine, seems like a prototype or a toy. Free! www.websnapr.com Tried using this, made a free account and requested a thumbnail. Waited a few minutes and refreshed a couple of times, and ended up having the account banned. Free is tricky yes, but if I can't try it out successfully I'm disinclined to pay. www.shrinktheweb.com Free account seems to be very quick. Lots of documentation on the site, and even covers local caching of the images to your own server (documentation mostly in PHP). Quality of thumbnails look good, and there appear to be sufficient options for setting thumbnail placeholder images and parameters for altering how the thumbnailing is done. Also supports large 'screenshots' of URLs - very useful for me. Discovered the PRO pricing is an à la carte menu, allowing me to select just the features I want and keep the monthly cost low. Excellent stuff, have decided to use this service. www.thumbalizr.com Good coverage of thumbnail sizes and control options - even allowing specification for browser width when thumbnailing. No ping-back, but I can live without that. Supports local caching of images with PHP API, would prefer .NET, but can port it if necessary. Looks like a fairly professional service but seems fairly expensive for the number of thumbnails you get to generate. apologies for lack of proper linking - spam protection! I'm not entirely convinced by any of them, and since this will be a long term service I'd like some stability and support. I'm willing to pay for the service, but I'd want something that fulfills most if not all of my requirements for that. I should also mention that we're hosted on Windows under IIS, so local solutions involving Xvfb and the like sadly can't be used for this project. So my question is: what services do you use? How have they panned out, are you happy with them?

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• Getting TypeError: Error #1009: Cannot access a property or method of a null object reference.

  - by nemade-vipin

  hello friends, I have created small application for login in flex desktop application. In which I am refering webservice method for login for this have created the Authentication class. Now I want to refer different Textinput value for mobile no and Textinput value for password. In my Authentication class. for this I have created the object of mxml class.And using this I am getting the mobile no value and password value in My Action script class. This my code :- SBTS.mxml file xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" public function login():void { var User:Authentication; User = new Authentication(); User.authentication(); } ]] text=" Select Child."/ Action script class :- package src { import adobe.utils.XMLUI; import generated.webservices.*; import mx.collections.ArrayCollection; import mx.controls.Alert; import mx.rpc.events.FaultEvent; public class Authentication { [ Bindable] private var childName:ArrayCollection; [ Bindable] private var childId:ArrayCollection; private var photoFeed:ArrayCollection; private var arrayOfchild:Array; private var newEntry:GetSBTSMobileAuthentication; public var user:SBTSWebService; public var mxmlobj:SBTS; public function authentication():void { user = new SBTSWebService(); if(user!=null) { user.addSBTSWebServiceFaultEventListener(handleFaults); user.addgetSBTSMobileAuthenticationEventListener(authenticationResult); newEntry = new GetSBTSMobileAuthentication(); if(newEntry!=null) { mxmlobj = new SBTS(); if(mxmlobj != null) { newEntry.mobile = mxmlobj.mobileno.text; // Getting error here error mention below newEntry.password= mxmlobj.password.text; } user.getSBTSMobileAuthentication(newEntry); } } } public function handleFaults(event:FaultEvent):void { Alert.show( "A fault occured contacting the server. Fault message is: " + event.fault.faultString); } public function authenticationResult(event:GetSBTSMobileAuthenticationResultEvent):void { if(event.result != null && event.result._return0) { if(event.result._return 0) { var UserId:int = event.result._return; if(mxmlobj != null) { mxmlobj.loginform.enabled = false; mxmlobj.viewstack2.selectedIndex=1; } } else { Alert.show( "Authentication fail"); } } } } } I am getting this error :- TypeError: Error #1009: Cannot access a property or method of a null object reference. at SBTSBusineesObject::Authentication/authentication()[E:\Users\User1\Documents\Fl ex Builder 3\SBTS\src\SBTSBusineesObject\Authentication.as:35] at SBTS/login()[E:\Users\User1\Documents\Flex Builder 3\SBTS\src\SBTS.mxml:12] at SBTS/___SBTS_Button1_click()[E:\Users\User1\Documents\Flex Builder 3\SBTS\src\SBTS.mxml:27] please help me to remove this error.

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• MBR Booting from DOS

  - by eflukx

  For a project I would like to invoke the MBR on the first harddisk directly from DOS. I've written a small assembler program that loads the MBR in memory at 0:7c00h an does a far jump to it. I've put my util on a bootable floppy. The disk (HD0, 0x80) i'm trying to boot has a TrueCrypt boot loader on it. It shows up the TrueCrypt screen, but after typing in the password it crashes the system. When I run my little utlility (w00t.com) on a normal WinXP machine it seams to crash immedealty. Apparently I'm forgetting some crucial stuff the BIOS normally does, my guess is it's something trivial. Can someone with better bare-metal DOS and BIOS experience help me out? Heres my code: .MODEL tiny .386 _TEXT SEGMENT USE16 INCLUDE BootDefs.i ORG 100h start: ; http://vxheavens.com/lib/vbw05.html ; Before DOS has booted the BIOS stores the amount of usable lower memory ; in a word located at 0:413h in memory. We going to erase this value because ; we have booted dos before loading the bootsector, and dos is fat (and ugly). ; fake free memory ;push ds ;push 0 ;pop ds ;mov ax, TC_BOOT_LOADER_SEGMENT / 1024 * 16 + TC_BOOT_MEMORY_REQUIRED ;mov word ptr ds:[413h], ax ;ax = memory in K ;pop ds ;lea si, memory_patched_msg ;call print ;mov ax, cs mov ax, 0 mov es, ax ; read first sector to es:7c00h (== cs:7c00) mov dl, 80h mov cl, 1 mov al, 1 mov bx, 7c00h ;load sector to es:bx call read_sectors lea si, mbr_loaded_msg call print lea si, jmp_to_mbr_msg call print ;Set BIOS default values in environment cli mov dl, 80h ;(drive C) xor ax, ax mov ds, ax mov es, ax mov ss, ax mov sp, 0ffffh sti push es push 7c00h retf ;Jump to MBR code at 0:7c00h ; Print string print: xor bx, bx mov ah, 0eh cld @@: lodsb test al, al jz print_end int 10h jmp @B print_end: ret ; Read sectors of the first cylinder read_sectors: mov ch, 0 ; Cylinder mov dh, 0 ; Head ; DL = drive number passed from BIOS mov ah, 2 int 13h jnc read_ok lea si, disk_error_msg call print read_ok: ret memory_patched_msg db 'Memory patched', 13, 10, 7, 0 mbr_loaded_msg db 'MBR loaded', 13, 10, 7, 0 jmp_to_mbr_msg db 'Jumping to MBR code', 13, 10, 7, 0 disk_error_msg db 'Disk error', 13, 10, 7, 0 _TEXT ENDS END start

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• Good Secure Backups Developers at Home

  - by slashmais

  What is a good, secure, method to do backups, for programmers who do research & development at home and cannot afford to lose any work? Conditions: The backups must ALWAYS be within reasonably easy reach. Internet connection cannot be guaranteed to be always available. The solution must be either FREE or priced within reason, and subject to 2 above. Status Report This is for now only considering free options. The following open-source projects are suggested in the answers (here & elsewhere): BackupPC is a high-performance, enterprise-grade system for backing up Linux, WinXX and MacOSX PCs and laptops to a server's disk. Storebackup is a backup utility that stores files on other disks. mybackware: These scripts were developed to create SQL dump files for basic disaster recovery of small MySQL installations. Bacula is [...] to manage backup, recovery, and verification of computer data across a network of computers of different kinds. In technical terms, it is a network based backup program. AutoDL 2 and Sec-Bk: AutoDL 2 is a scalable transport independant automated file transfer system. It is suitable for uploading files from a staging server to every server on a production server farm [...] Sec-Bk is a set of simple utilities to securely back up files to a remote location, even a public storage location. rsnapshot is a filesystem snapshot utility for making backups of local and remote systems. rbme: Using rsync for backups [...] you get perpetual incremental backups that appear as full backups (for each day) and thus allow easy restore or further copying to tape etc. Duplicity backs directories by producing encrypted tar-format volumes and uploading them to a remote or local file server. [...] uses librsync, [for] incremental archives Other Possibilities: Using a Distributed Version Control System (DVCS) such as Git(/Easy Git), Bazaar, Mercurial answers the need to have the backup available locally. Use free online storage space as a remote backup, e.g.: compress your work/backup directory and mail it to your gmail account. Strategies See crazyscot's answer

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