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  • Big-O for GPS data

    - by HH
    A non-critical GPS module use lists because it needs to be modifiable, new routes added, new distances calculated, continuos comparisons. Well so I thought but my team member wrote something I am very hard to get into. His pseudo code int k =0; a[][] <- create mapModuleNearbyDotList -array //CPU O(n) for(j = 1 to n) // O(nlog(m)) for(i =1 to n) for(k = 1 to n) if(dot is nearby) adj[i][j]=min(adj[i][j], adj[i][k] + adj[k][j]); His ideas transformations of lists to tables His worst case time complexity is O(n^3), where n is number of elements in his so-called table. Exception to the last point with Finite structure: O(mlog(n)) where n is number of vertices and m is an arbitrary constants Questions about his ideas why to waste resources to transform constantly-modified lists to table? Fast? only point where I to some extent agree but cannot understand the same upper limits n for each for-loops -- perhaps he supposed it circular why does the code take O(mlog(n)) to proceed in time as finite structure? The term finite may be wrong, explicit?

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  • GDI+ & Delphi, PNG resource, DrawImage, ColorConversion -> Out of Memory

    - by Paul
    I have started to toy around with GDI+ in Delphi 2009. Among the things that I wanted to do was to load a PNG resource and apply a Color Conversion to it when drawing it to the Graphics object. I am using the code provided in http://www.bilsen.com/gdiplus/. To do that I just added a new constructor to TGPBitmap that uses the same code found in <www.codeproject.com>/KB/GDI-plus/cgdiplusbitmap.aspx (C++) or <www.masm32.com>/board/index.php?topic=10191.0 (MASM) converted to Delphi. For reference, the converted code is as follows: constructor TGPBitmap.Create(const Instance: HInst; const PngName: String; dummy : PngResource_t); const cPngType : string = 'PNG'; var hResource : HRSRC; imageSize : DWORD; pResourceData : Pointer; hBuffer : HGLOBAL; pBuffer : Pointer; pStream : IStream; begin inherited Create; hResource := FindResource(Instance, PWideChar(PngName), PWideChar(cPngType)); if hResource = 0 then Exit; imageSize := SizeofResource(Instance, hResource); if imageSize = 0 then Exit; pResourceData := LockResource(LoadResource(Instance, hResource)); if pResourceData = nil then Exit; hBuffer := GlobalAlloc(GMEM_MOVEABLE, imageSize); if hBuffer <> 0 then begin try pBuffer := GlobalLock(hBuffer); if pBuffer <> nil then begin try CopyMemory(pBuffer, pResourceData, imageSize); if CreateStreamOnHGlobal(hBuffer, FALSE, pStream) = S_OK then begin GdipCheck(GdipCreateBitmapFromStream(pStream, FNativeHandle)); end; finally GlobalUnlock(hBuffer); pStream := nil; end; end; finally GlobalFree(hBuffer); end; end; end; The code seems to work fine as I am able to draw the loaded image without any problems. However, if I try to apply a Color Conversion when drawing it, then I get a lovely error: (GDI+ Error) Out of Memory. If I load the bitmap from a file, or if I create a temporary to which I draw the initial bitmap and then use the temporary, then it works just fine. What bugs me is that if I take the C++ project from codeproject, add the same PNG as resource and use the same color conversion (in other words, do the exact same thing I am doing in Delphi in the same order and with the same function calls that happen to go to the same DLL), then it works. The C++ code looks like this: const Gdiplus::ColorMatrix cTrMatrix = { { {1.0, 0.0, 0.0, 0.0, 0.0}, {0.0, 1.0, 0.0, 0.0, 0.0}, {0.0, 0.0, 1.0, 0.0, 0.0}, {0.0, 0.0, 0.0, 0.5, 0.0}, {0.0, 0.0, 0.0, 0.0, 1.0} } }; Gdiplus::ImageAttributes imgAttrs; imgAttrs.SetColorMatrix(&cTrMatrix, Gdiplus::ColorMatrixFlagsDefault, Gdiplus::ColorAdjustTypeBitmap); graphics.DrawImage(*pBitmap, Gdiplus::Rect(0, 0, pBitmap->m_pBitmap->GetWidth(), pBitmap->m_pBitmap->GetHeight()), 0, 0, pBitmap->m_pBitmap->GetWidth(), pBitmap->m_pBitmap->GetHeight(), Gdiplus::UnitPixel, &imgAttrs); The Delphi counterpart is: const cTrMatrix: TGPColorMatrix = ( M: ((1.0, 0.0, 0.0, 0.0, 0.0), (0.0, 1.0, 0.0, 0.0, 0.0), (0.0, 0.0, 1.0, 0.0, 0.0), (0.0, 0.0, 0.0, 0.5, 0.0), (0.0, 0.0, 0.0, 0.0, 1.0))); var lImgAttrTr : IGPImageAttributes; lBitmap : IGPBitmap; begin // ... lImgAttrTr := TGPImageAttributes.Create; lImgAttrTr.SetColorMatrix(cTrMatrix, ColorMatrixFlagsDefault, ColorAdjustTypeBitmap); aGraphics.DrawImage ( lBitmap, TGPRect.Create ( 0, 0, lBitmap.Width, lBitmap.Height ), 0, 0, lBitmap.Width, lBitmap.Height, UnitPixel, lImgAttrTr ); I am completely clueless as to what may be causing the issue, and Google has not been of any help. Any ideas, comments and explanations are highly appreciated.

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  • Using JMX classes to notify on events over time

    - by Cincinnati Joe
    I've been looking at JMX for monitoring application and system metrics (partially because MBeans can accessed by various tools such as JConsole). It would seem like the classes included with JMX would be useful for things like notification when metrics have exceeded thresholds. But I'm not sure they fit with the way I want to measure these over a specified time period. For example, let's say I want to notify an admin when the average CPU load is over 95% for more than 5 minutes. Is that something can be done with a GaugeMonitor? From the docs, it doesn't seem quite suited for this, and I'm wondering if instead I should write my own MBean with the necessary logic. A more relevant example is when the login times for users exceed 10s over a period of 5 mins. Slightly different would be the last 20 logins took more than 10s on average. Another case would be when a process crashes 4+ times in an hour. Or the request queue exceeds 15 for 5 mins. Are the JMX Monitor classes useful for this kind of thing?

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  • trouble calculating offset index into 3D array

    - by Derek
    Hello, I am writing a CUDA kernel to create a 3x3 covariance matrix for each location in the rows*cols main matrix. So that 3D matrix is rows*cols*9 in size, which i allocated in a single malloc accordingly. I need to access this in a single index value the 9 values of the 3x3 covariance matrix get their values set according to the appropriate row r and column c from some other 2D arrays. In other words - I need to calculate the appropriate index to access the 9 elements of the 3x3 covariance matrix, as well as the row and column offset of the 2D matrices that are inputs to the value, as well as the appropriate index for the storage array. i have tried to simplify it down to the following: //I am calling this kernel with 1D blocks who are 512 cols x 1row. TILE_WIDTH=512 int bx = blockIdx.x; int by = blockIdx.y; int tx = threadIdx.x; int ty = threadIdx.y; int r = by + ty; int c = bx*TILE_WIDTH + tx; int offset = r*cols+c; int ndx = r*cols*rows + c*cols; if((r < rows) && (c < cols)){ //this IF statement is trying to avoid the case where a threadblock went bigger than my original array..not sure if correct d_cov[ndx + 0] = otherArray[offset]; d_cov[ndx + 1] = otherArray[offset] d_cov[ndx + 2] = otherArray[offset] d_cov[ndx + 3] = otherArray[offset] d_cov[ndx + 4] = otherArray[offset] d_cov[ndx + 5] = otherArray[offset] d_cov[ndx + 6] = otherArray[offset] d_cov[ndx + 7] = otherArray[offset] d_cov[ndx + 8] = otherArray[offset] } When I check this array with the values calculated on the CPU, which loops over i=rows, j=cols, k = 1..9 The results do not match up. in other words d_cov[i*rows*cols + j*cols + k] != correctAnswer[i][j][k] Can anyone give me any tips on how to sovle this problem? Is it an indexing problem, or some other logic error?

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  • Programming Environment for a Motorola 68000 in Linux

    - by Nick Presta
    Greetings all, I am taking a Structure and Application of Microcomputers course this semester and we're programming with the Motorola 68000 series CPU/board. The course syllabus suggests running something like Easy68K or Teesside Motorola 68000 Assembler/Emulator at home to test our programs. I told my prof I run x64 Linux and asked what sort of environment I would need to complete my coursework. He said that the easiest environment to use is a Windows XP 32bit VM with one of the two suggested applications installed, however, he doesn't really care what I use as long as I can test what I write at home. So I'm asking if there exists some sort of emulator or environment for Linux so I can test my code, and what sort of caveats I will run into by writing and testing my code in Linux. Also, I plan to do my editing in Vim, which probably isn't a problem, but I would like any insight into editors for 68000 assembly, if you have any. Thanks! EDIT: Just to clarify - I don't want to install Linux on the board at all - I want to program on my home machine, test the code locally, and then bring it onto the board for grading/running.

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  • Queuing using table or MSMQ?

    - by Lieven Cardoen
    A part of the application I'm working on is an swf that shows a test with some 80 questions. Each question is saved to a sql server through WebORB and asp.net. If a candidate finisheds the test, the session needs to be validated. Problem now is that sometimes 350 candidates finish their test at the same moment, and cpu on webserver and sql server explodes (350 validations concurrently). Now, how would I implement queuing here? In the database, there's a table that has a record for each session. One column holds the status. 1 is finished, 2 is validated. I could implement queuing in two ways (as I see it, maybe you have other propositions): A process that checks the table for records with status 1. If it finds one, it validates the session. So, sessions are validated one after one. If a candidate finishes its session, a message is sent to a MSMQ queue. Another process listens to the queue and validates sessions one after one. Now, What would be the best approach? Where do you start the process that will validate sessions? In your global.asax (application_start)? As a windows service? As an exe on the root of the website that is started in application_start? To me, using the table and looking for records with status 1 seems the easiest way.

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  • Simple POSIX threads question

    - by Andy
    Hi, I have this POSIX thread: void subthread(void) { while(!quit_thread) { // do something ... // don't waste cpu cycles if(!quit_thread) usleep(500); } // free resources ... // tell main thread we're done quit_thread = FALSE; } Now I want to terminate subthread() from my main thread. I've tried the following: quit_thread = TRUE; // wait until subthread() has cleaned its resources while(quit_thread); But it does not work! The while() clause does never exit although my subthread clearly sets quit_thread to FALSE after having freed its resources! If I modify my shutdown code like this: quit_thread = TRUE; // wait until subthread() has cleaned its resources while(quit_thread) usleep(10); Then everything is working fine! Could someone explain to me why the first solution does not work and why the version with usleep(10) suddenly works? I know that this is not a pretty solution. I could use semaphores/signals for this but I'd like to learn something about multithreading, so I'd like to know why my first solution doesn't work. Thanks!

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  • Deploy to web container, bundle web container or embed web container...

    - by Jason
    I am developing an application that needs to be as simple as possible to install for the end user. While the end users will likely be experience Linux users (or sales engineers), they don't really know anything about Tomcat, Jetty, etc, nor do I think they should. So I see 3 ways to deploy our applications. I should also state that this is the first app that I have had to deploy that had a web interface, so I haven't really faced this question before. First is to deploy the application into an existing web container. Since we only deploy to Suse or RedHat this seems easy enough to do. However, we're not big on the idea of multiple apps running in one web container. It makes it harder to take down just one app. The next option is to just bundle Tomcat or Jetty and have the startup/shutdown scripts launch our bundled web container. Or 3rd, embed.. This will probably provide the same user experience as the second option. I'm curious what others do when faced with this problem to make it as fool proof as possible on the end user. I've almost ruled out deploying into an existing web container as we often like to set per application resource limits and CPU affinity, which I believe would affect all apps deployed into a web container/app server and not just a specific application. Thank you.

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  • Standard term for a thread I/O reorder buffer?

    - by Crashworks
    I have a case where many threads all concurrently generate data that is ultimately written to one long, serial file. I need to somehow serialize these writes so that the file gets written in the right order. ie, I have an input queue of 2048 jobs j0..jn, each of which produces a chunk of data oi. The jobs run in parallel on, say, eight threads, but the output blocks have to appear in the file in the same order as the corresponding input blocks — the output file has to be in the order o0o1o2... The solution to this is pretty self evident: I need some kind of buffer that accumulates and writes the output blocks in the correct order, similar to a CPU reorder buffer in Tomasulo's algorithm, or to the way that TCP reassembles out-of-order packets before passing them to the application layer. Before I go code it, I'd like to do a quick literature search to see if there are any papers that have solved this problem in a particularly clever or efficient way, since I have severe realtime and memory constraints. I can't seem to find any papers describing this though; a Scholar search on every permutation of [threads, concurrent, reorder buffer, reassembly, io, serialize] hasn't yielded anything useful. I feel like I must just not be searching the right terms. Is there a common academic name or keyword for this kind of pattern that I can search on?

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  • Different programming languages possibilities

    - by b-gen-jack-o-neill
    Hello. This should be very simple question. There are many programming languages out there, compiled into machine code or managed code. I first started with ASM back in high school. Assembler is very nice, since you know what exactly CPU does. Next, (as you can see from my other questions here) I decided to learn C and C++. I choosed C becouse from what I read it is the language with output most close to assembler-written programs. But, what I want to know is, can any other Windows programming language out there call win32 API? To be exact, like C has its special header and functions for win32 api interactions, is this assumed to be some important part of programming language? Or are there any languages that have no support for calling win32 API, or just use console to IO and some functions for basic file IO? Becouse, for Windows programming with graphic output, it is essential to have acess to win32 API. I know this question might seem silly, but still please, help me, I ask for study porposes. Thanks.

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  • Why is CoRegisterClassObject creating two extra threads?

    - by Stijn Sanders
    I'm trying to fix a problem that only recently happens on a number of machine's on a VPN. They each run a client application I wrote that exposes a COM automation object. For some strange reason I haven't been able to discover yet, one thread in the application takes up all of the available CPU time, slowing other operation on the machine. In observing the application's strange behaviour, I've noticed it's the third thread started, and if I debug on my machine I notice the first call to CoRegisterClassObject created two extra threads. If the second of these two threads is the one that gets into an infinite loop, I'm not at all shure how to fix this. Where could I check next about what's wrong? Could it have started by one of the recent patches rolled out by Microsoft this last 'patch tuesday'? I had a go with ProcessExplorer to extract a stack trace of the thread: ntoskrnl.exe!ExReleaseResourceLite+0x1a3 ntoskrnl.exe!PsGetContextThread+0x329 WLDAP32.dll!Ordinal325+0x1231 WLDAP32.dll!Ordinal325+0x129e WLDAP32.dll!Ordinal325+0x1178 ntdll.dll!LdrInitializeThunk+0x24 ntdll.dll!LdrShutdownThread+0xe9 kernel32.dll!ExitThread+0x3e kernel32.dll!FreeLibraryAndExitThread+0x1e ole32.dll!StringFromGUID2+0x65d kernel32.dll!GetModuleFileNameA+0x1ba

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  • I need to make a multithreading program (python)

    - by Andreawu98
    import multiprocessing import time from itertools import product out_file = open("test.txt", 'w') P = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p','q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',] N = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] M = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'] c = int(input("Insert the number of digits you want: ")) n = int(input("If you need number press 1: ")) m = int(input("If you need upper letters press 1: ")) i = [] if n == 1: P = P + N if m == 1: P = P + M then = time.time() def worker(): for i in product(P, repeat=c): #check every possibilities k = '' for z in range(0, c): # k = k + str(i[z]) # print each possibility in a txt without parentesis or comma out_file.write( k + '\n') # out_file.close() now = time.time() diff = str(now - then) # To see how long does it take print(diff) worker() time.sleep(10) # just to check console The code check every single possibility and print it out in a test.txt file. It works but I really can't understand how can I speed it up. I saw it use 1 core out of my quad core CPU so I thought Multi-threading might work even though I don't know how. Please help me. Sorry for my English, I am from Italy.

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  • How much is too much memory allocation in NDK?

    - by Maximus
    The NDK download page notes that, "Typical good candidates for the NDK are self-contained, CPU-intensive operations that don't allocate much memory, such as signal processing, physics simulation, and so on." I came from a C background and was excited to try to use the NDK to operate most of my OpenGL ES functions and any native functions related to physics, animation of vertices, etc... I'm finding that I'm relying quite a bit on Native code and wondering if I may be making some mistakes. I've had no trouble with testing at this point, but I'm curious if I may run into problems in the future. For example, I have game struct defined (somewhat like is seen in the San-Angeles example). I'm loading vertex information for objects dynamically (just what is needed for an active game area) so there's quite a bit of memory allocation happening for vertices, normals, texture coordinates, indices and texture graphic data... just to name the essentials. I'm quite careful about freeing what is allocated between game areas. Would I be safer setting some caps on array sizes or should I charge bravely forward as I'm going now?

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  • c++ floating point precision loss: 3015/0.00025298219406977296

    - by SigTerm
    The problem. Microsoft Visual C++ 2005 compiler, 32bit windows xp sp3, amd 64 x2 cpu. Code: double a = 3015.0; double b = 0.00025298219406977296; //*((unsigned __int64*)(&a)) == 0x40a78e0000000000 //*((unsigned __int64*)(&b)) == 0x3f30945640000000 double f = a/b;//3015/0.00025298219406977296; the result of calculation (i.e. "f") is 11917835.000000000 (*((unsigned __int64*)(&f)) == 0x4166bb4160000000) although it should be 11917834.814763514 (i.e. *((unsigned __int64*)(&f)) == 0x4166bb415a128aef). I.e. fractional part is lost. Unfortunately, I need fractional part to be correct. Questions: 1) Why does this happen? 2) How can I fix the problem? Additional info: 0) The result is taken directly from "watch" window (it wasn't printed, and I didn't forget to set printing precision). I also provided hex dump of floating point variable, so I'm absolutely sure about calculation result. 1) The disassembly of f = a/b is: fld qword ptr [a] fdiv qword ptr [b] fstp qword ptr [f] 2) f = 3015/0.00025298219406977296; yields correct result (f == 11917834.814763514 , *((unsigned __int64*)(&f)) == 0x4166bb415a128aef ), but it looks like in this case result is simply calculated during compile-time: fld qword ptr [__real@4166bb415a128aef (828EA0h)] fstp qword ptr [f] So, how can I fix this problem? P.S. I've found a temporary workaround (i need only fractional part of division, so I simply use f = fmod(a/b)/b at the moment), but I still would like to know how to fix this problem properly - double precision is supposed to be 16 decimal digits, so such calculation isn't supposed to cause problems.

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  • Can knowing C actually hurt the code you write in higher level languages?

    - by Jurily
    The question seems settled, beaten to death even. Smart people have said smart things on the subject. To be a really good programmer, you need to know C. Or do you? I was enlightened twice this week. The first one made me realize that my assumptions don't go further than my knowledge behind them, and given the complexity of software running on my machine, that's almost non-existent. But what really drove it home was this Slashdot comment: The end result is that I notice the many naive ways in which traditional C "bare metal" programmers assume that higher level languages are implemented. They make bad "optimization" decisions in projects they influence, because they have no idea how a compiler works or how different a good runtime system may be from the naive macro-assembler model they understand. Then it hit me: C is just one more abstraction, like all others. Even the CPU itself is only an abstraction! I've just never seen it break, because I don't have the tools to measure it. I'm confused. Has my mind been mutilated beyond recovery, like Dijkstra said about BASIC? Am I living in a constant state of premature optimization? Is there hope for me, now that I realized I know nothing about anything? Is there anything to know, even? And why is it so fascinating, that everything I've written in the last five years might have been fundamentally wrong? To sum it up: is there any value in knowing more than the API docs tell me? EDIT: Made CW. Of course this also means now you must post examples of the interpreter/runtime optimizing better than we do :)

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  • Was Visual Studio 2008 or 2010 written to use multi cores?

    - by Erx_VB.NExT.Coder
    basically i want to know if the visual studio IDE and/or compiler in 2010 was written to make use of a multi core environment (i understand we can target multi core environments in 08 and 10, but that is not my question). i am trying to decide on if i should get a higher clock dual core or a lower clock quad core, as i want to try and figure out which processor will give me the absolute best possible experience with Visual Studio 2010 (ide and background compiler). if they are running the most important section (background compiler and other ide tasks) in one core, then the core will get cut off quicker if running a quad core, esp if background compiler is the heaviest task, i would imagine this would b e difficult to seperate in more then one process, so even if it uses multi cores you might still be better off with going for a higher clock cpu if the majority of the processing is still bound to occur in one core (ie the most significant part of the VS environment). i am a vb programmer, they've made great performance improvements in beta 2, congrats, but i would love to be able to use VS seamlessly... anyone have any ideas? thanks, erx

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  • What hash algorithms are parallelizable? Optimizing the hashing of large files utilizing on multi-co

    - by DanO
    I'm interested in optimizing the hashing of some large files (optimizing wall clock time). The I/O has been optimized well enough already and the I/O device (local SSD) is only tapped at about 25% of capacity, while one of the CPU cores is completely maxed-out. I have more cores available, and in the future will likely have even more cores. So far I've only been able to tap into more cores if I happen to need multiple hashes of the same file, say an MD5 AND a SHA256 at the same time. I can use the same I/O stream to feed two or more hash algorithms, and I get the faster algorithms done for free (as far as wall clock time). As I understand most hash algorithms, each new bit changes the entire result, and it is inherently challenging/impossible to do in parallel. Are any of the mainstream hash algorithms parallelizable? Are there any non-mainstream hashes that are parallelizable (and that have at least a sample implementation available)? As future CPUs will trend toward more cores and a leveling off in clock speed, is there any way to improve the performance of file hashing? (other than liquid nitrogen cooled overclocking?) or is it inherently non-parallelizable?

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  • are mobile can be used as a devices to develop application

    - by Richa Media and services
    I say that we can work @ mobile using a technique and work with any IDE and use any OS without problem like work on visual studio and use Window 7 How it possible ? 1. We use Mobile like a CPU and Use a monitor to watch code. We use samsung's techniques to display on monitor. it's give signal to monitor wirelessly to display code on monitor 2 We use Wireless keyboard and Mouse (if user like USB then he also use USB keyboard and mouse) 3. We use a component inside of mobile to control all devices like internet , wi-fi bluethoth. by component user easily setup , control and use feature. 4 don't be confused. i am sure to say that we not use mobile to watch code on mobile screen and Mobile 's keyboard because it's too smaller to work so we use Monitor (LCD) to display code and a keyboard to work comfortably and freely. 5. what are you think if you see a developer who work using this way 6. it is not impossible. give me some feedback and suggestion about your thinking on this technologies.

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  • DirectX: Game loop order, draw first and then handle input?

    - by Ricket
    I was just reading through the DirectX documentation and encountered something interesting in the page for IDirect3DDevice9::BeginScene : To enable maximal parallelism between the CPU and the graphics accelerator, it is advantageous to call IDirect3DDevice9::EndScene as far ahead of calling present as possible. I've been accustomed to writing my game loop to handle input and such, then draw. Do I have it backwards? Maybe the game loop should be more like this: (semi-pseudocode, obviously) while(running) { d3ddev->Clear(...); d3ddev->BeginScene(); // draw things d3ddev->EndScene(); // handle input // do any other processing // play sounds, etc. d3ddev->Present(NULL, NULL, NULL, NULL); } According to that sentence of the documentation, this loop would "enable maximal parallelism". Is this commonly done? Are there any downsides to ordering the game loop like this? I see no real problem with it after the first iteration... And I know the best way to know the actual speed increase of something like this is to actually benchmark it, but has anyone else already tried this and can you attest to any actual speed increase?

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  • JAR files, don't they just bloat and slow Java down?

    - by Josamoto
    Okay, the question might seem dumb, but I'm asking it anyways. After struggling for hours to get a Spring + BlazeDS project up and running, I discovered that I was having problems with my project as a result of not including the right dependencies for Spring etc. There were .jars missing from my WEB-INF/lib folder, yes, silly me. After a while, I managed to get all the .jar files where they belong, and it comes at a whopping 12.5MB at that, and there's more than 30 of them! Which concerns me, but it probably and hopefully shouldn't be concerned. How does Java operate in terms of these JAR files, they do take up quite a bit of hard drive space, taking into account that it's compressed and compiled source code. So that can really quickly populate a lot of RAM and in an instant. My questions are: Does Java load an entire .jar file into memory when say for instance a class in that .jar is instantiated? What about stuff that's in the .jar that never gets used. Do .jars get cached somehow, for optimized application performance? When a single .jar is loaded, I understand that the thing sits in memory and is available across multiple HTTP requests (i.e. for the lifetime of the server instance running), unlike PHP where objects are created on the fly with each request, is this assumption correct? When using Spring, I'm thinking, I had to include all those fiddly .jars, wouldn't I just be better off just using native Java, with say at least and ORM solution like Hibernate? So far, Spring just took extra time configuring, extra hard drive space, extra memory, cpu consumption, so I'm concerned that the framework is going to cost too much application performance just to get for example, IoC implemented with my BlazeDS server. There still has to come ORM, a unit testing framework and bits and pieces here and there. It's just so easy to bloat up a project quickly and irresponsibly easily. Where do I draw the line?

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  • Flash browser game - HTTP + PHP vs Socket + Something else

    - by Maurycy Zarzycki
    I am developing a non-real time browser RPG game (think Kingdom of Loathing) which would be played from within a Flash app. At first I just wanted to make the communication with server using simply URLLoader to tell PHP what I am doing, and using $_SESSION to store data needed in-between request. I wonder if it wouldn't be better to base it on a socket connection, an app residing on a server written in Java or Python. The problem is I have never ever written such an app so I have no idea how much I'd have to "shift" my thoughts from simple responding do request (like PHP) to continuously working application. I won't hide I am also concerned about the memory and CPU usage of such Server app, when for example there would be hundreds of users connected. I've done some research. I have tried to do some research, but thanks to my nil knowledge on the sockets subject I haven't found anything helpful. So, considering the fact I don't need real time data exchange, will it be wise to develop the server side part as socket server, not in plain ol' PHP?

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  • Codeigniter: Controller URI with Library

    - by Kevin Brown
    I have a working controller and library function, but I now need to pass a URI segment to the library for decision making, and I'm stuck. Controller: function survey($method) { $id = $this->session->userdata('id'); $data['member'] = $this->home_model->getUser($id); //Convert the db Object to a row array $data['manager'] = $data['member']->row(); $manager_id = $data['manager']->manager_id; $data['manager'] = $this->home_model->getUser($manager_id); $data['manager'] = $data['manager']->row(); if ($data['manager']->credits == '0') { flashMsg('warning',"You can't complete the assessment until your manager has purchased credit."); redirect('home','location'); } elseif ($data['manager']->test_complete == '3'){ flashMsg('warning',"You already completed the Assessment."); redirect('home','location'); } else{ $data['header'] = "Home"; $this->survey_form_processing->survey_form($this->_container,$data); } } Library: function survey_form($container) { if($method ==1){ $id = $this->CI->session->userdata('id'); // Setup fields for($i=1;$i<18;$i++){ $fields["a_".$i] = 'Question '.$i; } for($i=1;$i<17;$i++){ $fields["b_".$i] = 'Question '.$i; } $fields["company_name"] = "Company Name"; $fields['company_address'] = "company_address"; $fields['company_phone'] = "company_phone"; $fields['company_state'] = "company_state"; $fields['company_city'] = "company_city"; $fields['company_zip'] = "company_zip"; $fields['job_title'] = "job_title"; $fields['job_type'] = "job_type"; $fields['job_time'] = "job_time"; $fields['department'] = "department"; $fields['supervisor'] = "supervisor"; $fields['vision'] = "vision"; $fields['height'] = "height"; $fields['weight'] = "weight"; $fields['hand_dominance'] = "hand_dominance"; $fields['areas_of_fatigue'] = "areas_of_fatigue"; $fields['injury_review'] = "injury_review"; $fields['job_positive'] = "job_positive"; $fields['risk_factors'] = "risk_factors"; $fields['job_improvement_short'] = "job_improvement_short"; $fields['job_improvement_long'] = "job_improvement_long"; $fields["c_1"] = "Near Lift"; $fields["c_2"] = "Middle Lift"; $fields["c_3"] = "Far Lift"; $this->CI->validation->set_fields($fields); // Set Rules for($i=1;$i<18;$i++){ $rules["a_".$i]= 'hour|integer|max_length[2]'; } for($i=1;$i<17;$i++){ $rules["b_".$i]= 'hour|integer|max_length[2]'; } // Setup form default values $this->CI->validation->set_rules($rules); if ( $this->CI->validation->run() === FALSE ) { // Output any errors $this->CI->validation->output_errors(); } else { // Submit form $this->_submit(); } // Modify form, first load $this->CI->db->from('be_user_profiles'); $this->CI->db->where('user_id' , $id); $user = $this->CI->db->get(); $this->CI->db->from('be_survey'); $this->CI->db->where('user_id' , $id); $survey = $this->CI->db->get(); $user = array_merge($user->row_array(),$survey->row_array()); $this->CI->validation->set_default_value($user); // Display page $data['user'] = $user; $data['header'] = 'Risk Assessment Survey'; $data['page'] = $this->CI->config->item('backendpro_template_public') . 'form_survey'; $this->CI->load->view($container,$data); } else{ redirect('home','location'); } } My library function doesn't know what to do with Method...and I'm confused. Does it have something to do with instances in my library?

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  • Using my custom colormap in Java for images

    - by John
    Hi everyone! I've got a question concering a colormapping via index. I tried this code found on http://www.podgoretsky.pri.ee/ftp/Docs/Java/Tricks%20of%20the%20Java%20Programming%20Gurus/ch12.htm // Gradient.java // Imports import java.applet.Applet; import java.awt.; import java.awt.image.; public class Gradient extends Applet { final int colors = 32; final int width = 200; final int height = 200; Image img; public void init() { // Create the color map byte[] rbmap = new byte[colors]; byte[] gmap = new byte[colors]; for (int i = 0; i < colors; i++) gmap[i] = (byte)((i * 255) / (colors - 1)); // Create the color model int bits = (int)Math.ceil(Math.log(colors) / Math.log(2)); IndexColorModel model = new IndexColorModel(bits, colors, rbmap, gmap, rbmap); // Create the pixels int pixels[] = new int[width * height]; int index = 0; for (int y = 0; y < height; y++) for (int x = 0; x < width; x++) pixels[index++] = (x * colors) / width; // Create the image img = createImage(new MemoryImageSource(width, height, model, pixels, 0, width)); } public void paint(Graphics g) { g.drawImage(img, 0, 0, this); } } It worked great but I tried to load a custom image jpeg mapped on my own colormap but it didnt work right. I saw only a bunch of green and blue pixels drawn on a white background. My custom color map method here: public void inintByteArrays() { double[][] c = // basic color map { { 0.0000, 0.0000, 0.5625 }, { 0.0000, 0.0000, 0.6250 }, { 0.0000, 0.0000, 0.6875 }, { 0.0000, 0.0000, 0.6875 }, { 0.0000, 0.0000, 0.7500 }, { 0.0000, 0.0000, 0.8125 }, { 0.0000, 0.0000, 0.8750 }, { 0.0000, 0.0000, 0.9375 }, { 0.0000, 0.0000, 1.0000 }, { 0.0000, 0.0625, 1.0000 }, { 0.0000, 0.1250, 1.0000 }, { 0.0000, 0.1875, 1.0000 }, { 0.0000, 0.2500, 1.0000 }, { 0.0000, 0.3125, 1.0000 }, { 0.0000, 0.3750, 1.0000 }, { 0.0000, 0.4375, 1.0000 }, { 0.0000, 0.5000, 1.0000 }, { 0.0000, 0.5625, 1.0000 }, { 0.0000, 0.6250, 1.0000 }, { 0.0000, 0.6875, 1.0000 }, { 0.0000, 0.7500, 1.0000 }, { 0.0000, 0.8125, 1.0000 }, { 0.0000, 0.8750, 1.0000 }, { 0.0000, 0.9375, 1.0000 }, { 0.0000, 1.0000, 1.0000 }, { 0.0625, 1.0000, 0.9375 }, { 0.1250, 1.0000, 0.8750 }, { 0.1875, 1.0000, 0.8125 }, { 0.2500, 1.0000, 0.7500 }, { 0.3125, 1.0000, 0.6875 }, { 0.3750, 1.0000, 0.6250 }, { 0.4375, 1.0000, 0.5625 }, { 0.5000, 1.0000, 0.5000 }, { 0.5625, 1.0000, 0.4375 }, { 0.6250, 1.0000, 0.3750 }, { 0.6875, 1.0000, 0.3125 }, { 0.7500, 1.0000, 0.2500 }, { 0.8125, 1.0000, 0.1875 }, { 0.8750, 1.0000, 0.1250 }, { 0.9375, 1.0000, 0.0625 }, { 1.0000, 1.0000, 0.0000 }, { 1.0000, 0.9375, 0.0000 }, { 1.0000, 0.8750, 0.0000 }, { 1.0000, 0.8125, 0.0000 }, { 1.0000, 0.7500, 0.0000 }, { 1.0000, 0.6875, 0.0000 }, { 1.0000, 0.6250, 0.0000 }, { 1.0000, 0.5625, 0.0000 }, { 1.0000, 0.5000, 0.0000 }, { 1.0000, 0.4375, 0.0000 }, { 1.0000, 0.3750, 0.0000 }, { 1.0000, 0.3125, 0.0000 }, { 1.0000, 0.2500, 0.0000 }, { 1.0000, 0.1875, 0.0000 }, { 1.0000, 0.1250, 0.0000 }, { 1.0000, 0.0625, 0.0000 }, { 1.0000, 0.0000, 0.0000 }, { 0.9375, 0.0000, 0.0000 }, { 0.8750, 0.0000, 0.0000 }, { 0.8125, 0.0000, 0.0000 }, { 0.7500, 0.0000, 0.0000 }, { 0.6875, 0.0000, 0.0000 }, { 0.6250, 0.0000, 0.0000 }, { 0.5625, 0.0000, 0.0000 }, { 0.5000, 0.0000, 0.0000 } }; for (int i = 0; i < c.length; i++) { for (int j = 0; j < c[i].length; j++) { if (j == 0) r[i] = (byte) ((byte) c[i][j]*255); if (j == 1) g[i] = (byte) ((byte) c[i][j]*255); if (j == 2) b[i] = (byte) ((byte) c[i][j]*255); } } My question is how I can use my colormap for any image I want to load and map in the right way. Thank you very much! Greetings, protein1.

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  • A generic C++ library that provides QtConcurrent functionality?

    - by Lucas
    QtConcurrent is awesome. I'll let the Qt docs speak for themselves: QtConcurrent includes functional programming style APIs for parallel list processing, including a MapReduce and FilterReduce implementation for shared-memory (non-distributed) systems, and classes for managing asynchronous computations in GUI applications. For instance, you give QtConcurrent::map() an iterable sequence and a function that accepts items of the type stored in the sequence, and that function is applied to all the items in the collection. This is done in a multi-threaded manner, with a thread pool equal to the number of logical CPU's on the system. There are plenty of other function in QtConcurrent, like filter(), filteredReduced() etc. The standard CompSci map/reduce functions and the like. I'm totally in love with this, but I'm starting work on an OSS project that will not be using the Qt framework. It's a library, and I don't want to force others to depend on such a large framework like Qt. I'm trying to keep external dependencies to a minimum (it's the decent thing to do). I'm looking for a generic C++ framework that provides me with the same/similar high-level primitives that QtConcurrent does. AFAIK boost has nothing like this (I may be wrong though). boost::thread is very low-level compared to what I'm looking for. I know C# has something very similar with their Parallel Extensions so I know this isn't a Qt-only idea. What do you suggest I use?

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  • Windows 2008 VPS hosting experiences

    - by Luke Bennett
    Whilst similar questions exist, I couldn't find any which quite match my request. I'm looking for hosting for some personal .NET projects which for various reasons I do not want to host on our servers at work. I need to be able to host multiple sites and for that reason I'm thinking of a VPS with RDP access for the time being - don't fancy shared hosting as I feel that doesn't offer me the flexbility and control I'm looking for. What experiences do people have of Windows 2008 VPS providers? I've come across a few possibilities although it seems a lot of places are still on Windows 2003 with 2008 'coming soon'. Is VPS the best way to go? Eventually (depending on how the projects take off) I intend to get a dedicated box but at this stage it's not cost-effective. Also, what are people's experiences of running SQL Server Express on a VPS? What would you say the minimum requirements are for CPU/memory? I know it's not going to be anywhere near as performant as SQL Server 2005/8 running on a dedicated box but I'm hoping it will be an acceptable starting point. Any other tips/advice also welcome! Edit: Forgot to mention, I'm ideally looking for UK hosting although I'm open to alternatives.

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