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  • Manipulate multiple check boxes by ID using unobtrusive java script?

    - by Dean
    I want to be able to select multiple check boxes onmouseover, but instead of applying onmouseover to every individual box, I've been trying to work out how to do so by manipulating check boxes by ID instead, although I'm not sure where to go from using getElementById,. So instead of what you see below. <html> <head> <script> var Toggle = true; var Highlight=false; function handleKeyPress(evt) { var nbr; if (window.Event) nbr = evt.which; else nbr = event.keyCode; if(nbr==16)Highlight=true; return true; } function MakeFalse(){Highlight=false;} function SelectIt(X){ if(X.checked && Toggle)X.checked=false; else X.checked=true; } function ChangeText() { var test1 = document.getElementById("1"); test1.innerHTML = "onmouseover=SelectIt(this)" } </script> </head> <body> <form name="A"> <input type="checkbox" name="C1" onmouseover="SelectIt(this)" id="1"><br> <input type="checkbox" name="C2" onmouseover="SelectIt(this)" id="2"><br> <input type="checkbox" name="C3" onmouseover="SelectIt(this)" id="3"><br> <input type="checkbox" name="C4" onmouseover="SelectIt(this)" checked="" disabled="disabled" id="4"><br> <input type="checkbox" name="C5" onmouseover="SelectIt(this)" id="5"><br> <input type="checkbox" name="C6" onmouseover="SelectIt(this)" id="6"><br> <input type="checkbox" name="C7" onmouseover="SelectIt(this)" id="7"><br> <input type="checkbox" name="C8" onmouseover="SelectIt(this)" id="8"><br> </form> </body> </html> I want to be able to apply the onmousover effect to an array of check boxes like this <form name="A"> <input type="checkbox" name="C1" id="1"><br> <input type="checkbox" name="C2" id="2"><br> <input type="checkbox" name="C3" id="3"><br> <input type="checkbox" name="C4" checked="" disabled="disabled" id="4"><br> <input type="checkbox" name="C5" id="5"><br> <input type="checkbox" name="C6" id="6"><br> <input type="checkbox" name="C7" id="7"><br> <input type="checkbox" name="C8" id="8"><br> </form> After trying the search feature of stackoverflow.com and looking around on Google I haven't been able to a find a solution that makes sense to me thus far, although I'm still in the process of learning so I fear I might be trying to do something too advanced for my level of knowledge.

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  • ASP.MVC 1.0 complex ViewModel not populating on Action

    - by Graham
    Hi, I'm 3 days into learning MVC for a new project and i've managed to stumble my way over the multitude of issues I've come across - mainly about something as simple as moving data to a view and back into the controller in a type-safe (and manageable) manner. This is the latest. I've seen this reported before but nothing advised has seemed to work. I have a complex view model: public class IndexViewModel : ApplicationViewModel { public SearchFragment Search { get; private set; } public IndexViewModel() { this.Search = new SearchFragment(); } } public class SearchFragment { public string ItemId { get; set; } public string Identifier { get; set; } } This maps to (the main Index page): %@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<IndexViewModel>" %> <asp:Content ID="Content1" ContentPlaceHolderID="MainContent" runat="server"> <% Html.BeginForm("Search", AvailableControllers.Search, FormMethod.Post); %> <div id="search"> <% Html.RenderPartial("SearchControl", Model.Search); %> </div> <% Html.EndForm(); %> </asp:Content> and a UserControl: <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<SearchFragment>" %> <p> <label for="itemId"> <%= Html.Resource("ItemId") %></label> <%= Html.TextBox("itemId", Model.ItemId)%> </p> <p> <label for="title"> <%= Html.Resource("Title") %></label> <%= Html.TextBox("identifier", Model.Identifier)%> </p> <p> <input type="submit" value="<%= Html.Resource("Search") %>" name="search" /> </p> This is returned to the following method: [AcceptVerbs(HttpVerbs.Post)] public ActionResult Search(IndexViewModel viewModel) { .... } My problem is that when the view model is rehydrated from the View into the ViewModel, the SearchFragment elements are null. I suspect this is because the default model binder doesn't realise the HTML ItemId and Identifier elements rendered inline in the View map to the SearchFragment class. When I have two extra properties (ItemId and Identifier) in the IndexViewModel, the values are bound correctly. Unfortunately, as far as I can tell, I must use the SearchFragment as I need this to strongly type the Search UserControl... as the control can be used anywhere it can operate under any parent view. I really don't want to make it use "magic strings". There's too much of that going on already IMO. I've tried prefixing the HTML with "Search." in the hope that the model binder would recognise "Search.ItemId" and match to the IndexViewModel "Search" property and the ItemId within it, but this doesn't work. I fear I'm going to have to write my own ModelBinder to do this, but surely this must be something you can do out-of-the-box?? Failing that is there any other suggestions (or link to someone who has already done this?) Here's hoping....

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  • C++ vs Matlab vs Python as a main language for Computer Vision Postgraduate

    - by Hough
    Hi all, Firstly, sorry for a somewhat long question but I think that many people are in the same situation as me and hopefully they can also gain some benefit from this. I'll be starting my PhD very soon which involve the fields of computer vision, pattern recognition and machine learning. Currently, I'm using opencv (2.1) C++ interface and I especially like its powerful Mat class and the overloaded operations available for matrix and image seamless operations and transformations. I've also tried (and implemented many small vision projects) using opencv python interface (new bindings; opencv 2.1) and I really enjoy python's ability to integrate opencv, numpy, scipy and matplotlib. But recently, I went back to opencv C++ interface because I felt that the official python new bindings were not stable enough and no overloaded operations are available for matrices and images, not to mention the lack of machine learning modules and slow speeds in certain operations. I've also used Matlab extensively in the past and although I've used mex files and other means to speed up the program, I just felt that Matlab's performance was inadequate for real-time vision tasks, be it for fast prototyping or not. When the project becomes larger and larger, many tasks have to be re-written in C and compiled into Mex files increasingly and Matlab becomes nothing more than a glue language. Here comes the sub-questions: For postgrad studies in these fields (machine learning, vision, pattern recognition), what is your main or ideal programming language for rapid prototyping of ideas and testing algorithms contained in papers? For postgrad studies, can you list down the pros and cons of using the following languages? C++ (with opencv + gsl + svmlib + other libraries) vs Matlab (with all its toolboxes) vs python (with the imcomplete opencv bindings + numpy + scipy + matplotlib). Are there computer vision PhD/postgrad students here who are using only C++ (with all its availabe libraries including opencv) without even needing to resort to Matlab or python? In other words, given the current existing computer vision or machine learning libraries, is C++ alone sufficient for fast prototyping of ideas? If you're currently using Java or C# for your postgrad work, can you list down the reasons why they should be used and how they compare to other languages in terms of available libraries? What is the de facto vision/machine learning programming language and its associated libraries used in your university research group? Thanks in advance.

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  • Flash -> ByteArray -> AMFPHP -> Invalid Image !??

    - by undefined
    Hi, Im loading images into Flash and using JPGEncoder to encode the image to a ByteArray and send this to AMF PHP which writes out the bytearray to a file. This all appears to work correctly and I can download the resulting file in Photoshop CS4 absolutely fine. When i try to open it from the desktop or open it back in Flash it doesnt work... Picasa my default image browser says "Invalid" Here is the code i use to write the bytearray to a file - $jpg = $GLOBALS["HTTP_RAW_POST_DATA"]; file_put_contents($filename, $jpg); That's it ... I use the NetConnection class to connect and call the service, do I need to say Im sending jpg data? I assumed that JPGEncoder took care of that. How can I validate the bytearray before writing the file? Do I need to set MIME type or something .. excuse the slightly noob questions, a little knowledge can be a dangerous thing. Thanks --------------------------------------- PART II ------------------------------------------ Here is some code - 1) load the image into Flash player item.load(); function _onImageDataLoaded(evt:Event):void { var tmpFileRef:FileReference=FileReference(evt.target); image_loader=new Loader ; image_loader.contentLoaderInfo.addEventListener(Event.COMPLETE, _onImageLoaded); image_loader.loadBytes(tmpFileRef.data); } function _onImageLoaded(evt:Event):void { bitmap=Bitmap(evt.target.content); bitmap.smoothing=true; if (bitmap.width>MAX_WIDTH||bitmap.height>MAX_HEIGHT) { resizeBitmap(bitmap); } uploadResizedImage(bitmap); } function resizeBitmap(target:Bitmap):void { if (target.height>target.width) { target.width=MAX_WIDTH; target.scaleY=target.scaleX; } else if (target.width >= target.height) { target.height=MAX_HEIGHT; target.scaleX=target.scaleY; } } function uploadResizedImage(target:Bitmap):void { var _bmd:BitmapData=new BitmapData(target.width,target.height); _bmd.draw(target, new Matrix(target.scaleX, 0, 0, target.scaleY)); var encoded_jpg:JPGEncoder=new JPGEncoder(90); var jpg_binary:ByteArray=encoded_jpg.encode(_bmd); _uploadService=new NetConnection(); _uploadService.objectEncoding=ObjectEncoding.AMF3 _uploadService.connect("http://.../amfphp/gateway.php"); _uploadService.call("UploadService.receiveByteArray",new Responder(success, error), jpg_binary, currentImageFilename); } Many thanks for you help

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  • Loading, listing, and using R Modules and Functions in PL/R

    - by Dave Jarvis
    I am having difficulty with: Listing the R packages and functions available to PostgreSQL. Installing a package (such as Kendall) for use with PL/R Calling an R function within PostgreSQL Listing Available R Packages Q.1. How do you find out what R modules have been loaded? SELECT * FROM r_typenames(); That shows the types that are available, but what about checking if Kendall( X, Y ) is loaded? For example, the documentation shows: CREATE TABLE plr_modules ( modseq int4, modsrc text ); That seems to allow inserting records to dictate that Kendall is to be loaded, but the following code doesn't explain, syntactically, how to ensure that it gets loaded: INSERT INTO plr_modules VALUES (0, 'pg.test.module.load <-function(msg) {print(msg)}'); Q.2. What would the above line look like if you were trying to load Kendall? Q.3. Is it applicable? Installing R Packages Using the "synaptic" package manager the following packages have been installed: r-base r-base-core r-base-dev r-base-html r-base-latex r-cran-acepack r-cran-boot r-cran-car r-cran-chron r-cran-cluster r-cran-codetools r-cran-design r-cran-foreign r-cran-hmisc r-cran-kernsmooth r-cran-lattice r-cran-matrix r-cran-mgcv r-cran-nlme r-cran-quadprog r-cran-robustbase r-cran-rpart r-cran-survival r-cran-vr r-recommended Q.4. How do I know if Kendall is in there? Q.5. If it isn't, how do I find out what package it is in? Q.6. If it isn't in a package suitable for installing with apt-get (aptitude, synaptic, dpkg, what have you), how do I go about installing it on Ubuntu? Q.7. Where are the installation steps documented? Calling R Functions I have the following code: EXECUTE 'SELECT ' 'regr_slope( amount, year_taken ),' 'regr_intercept( amount, year_taken ),' 'corr( amount, year_taken ),' 'sum( measurements ) AS total_measurements ' 'FROM temp_regression' INTO STRICT slope, intercept, correlation, total_measurements; This code calls the PostgreSQL function corr to calculate Pearson's correlation over the data. Ideally, I'd like to do the following (by switching corr for plr_kendall): EXECUTE 'SELECT ' 'regr_slope( amount, year_taken ),' 'regr_intercept( amount, year_taken ),' 'plr_kendall( amount, year_taken ),' 'sum( measurements ) AS total_measurements ' 'FROM temp_regression' INTO STRICT slope, intercept, correlation, total_measurements; Q.8. Do I have to write plr_kendall myself? Q.9. Where can I find a simple example that walks through: Loading an R module into PG. Writing a PG wrapper for the desired R function. Calling the PG wrapper from a SELECT. For example, would the last two steps look like: create or replace function plr_kendall( _float8, _float8 ) returns float as ' agg_kendall(arg1, arg2) ' language 'plr'; CREATE AGGREGATE agg_kendall ( sfunc = plr_array_accum, basetype = float8, -- ??? stype = _float8, -- ??? finalfunc = plr_kendall ); And then the SELECT as above? Thank you!

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  • Extract information from conditional formula

    - by Ken Williams
    I'd like to write an R function that accepts a formula as its first argument, similar to lm() or glm() and friends. In this case, it's a function that takes a data frame and writes out a file in SVMLight format, which has this general form: <line> .=. <target> <feature>:<value> <feature>:<value> ... <feature>:<value> # <info> <target> .=. +1 | -1 | 0 | <float> <feature> .=. <integer> | "qid" <value> .=. <float> <info> .=. <string> for example, the following data frame: result qid f1 f2 f3 f4 f5 f6 f7 f8 1 -1 1 0.0000 0.1253 0.0000 0.1017 0.00 0.0000 0.0000 0.9999 2 -1 1 0.0098 0.0000 0.0000 0.0000 0.00 0.0316 0.0000 0.3661 3 1 1 0.0000 0.0000 0.1941 0.0000 0.00 0.0000 0.0509 0.0000 4 -1 2 0.0000 0.2863 0.0948 0.0000 0.34 0.0000 0.7428 0.0608 5 1 2 0.0000 0.0000 0.0000 0.4347 0.00 0.0000 0.9539 0.0000 6 1 2 0.0000 0.7282 0.9087 0.0000 0.00 0.0000 0.0000 0.0355 would be represented as follows: -1 qid:1 2:0.1253 4:0.1017 8:0.9999 -1 qid:1 1:0.0098 6:0.0316 8:0.3661 1 qid:1 3:0.1941 7:0.0509 -1 qid:2 2:0.2863 3:0.0948 5:0.3400 7:0.7428 8:0.0608 1 qid:2 4:0.4347 7:0.9539 1 qid:2 2:0.7282 3:0.9087 8:0.0355 The function I'd like to write would be called something like this: write.svmlight(result ~ f1+f2+f3+f4+f5+f6+f7+f8 | qid, data=mydata, file="out.txt") Or even write.svmlight(result ~ . | qid, data=mydata, file="out.txt") But I can't figure out how to use model.matrix() and/or model.frame() to know what columns it's supposed to write. Are these the right things to be looking at? Any help much appreciated!

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  • OpenCV 2.4.2 on Matlab 2012b (Windows 7)

    - by Maik Xhani
    Hello i am trying to use OpenCV 2.4.2 in Matlab 2012b. I have tried those actions: downloaded OpenCV 2.4.2 used CMake on opencv folder using Visual Studio 10 and Visual Studio 10 Win64 compiler built Debug and Release version with Visual Studio first without any other option and then with D_SCL_SECURE=1 specified for every project changed Matlab's mexopts.bat and adding new lines refering to library and include (see bottom for mexopts.bat content) with Visual Studio 10 compiler tried to compile a simple file with a OpenCV library inclusion and all goes well. try to compile something that actually uses OpenCV commands and get errors. I used openmexopencv library and when tried to compile something i get this error cv.make mex -largeArrayDims -D_SECURE_SCL=1 -Iinclude -I"C:\OpenCV\build\include" -L"C:\OpenCV\build\x64\vc10\lib" -lopencv_calib3d242 -lopencv_contrib242 -lopencv_core242 -lopencv_features2d242 -lopencv_flann242 -lopencv_gpu242 -lopencv_haartraining_engine -lopencv_highgui242 -lopencv_imgproc242 -lopencv_legacy242 -lopencv_ml242 -lopencv_nonfree242 -lopencv_objdetect242 -lopencv_photo242 -lopencv_stitching242 -lopencv_ts242 -lopencv_video242 -lopencv_videostab242 src+cv\CamShift.cpp lib\MxArray.obj -output +cv\CamShift CamShift.cpp C:\Program Files\MATLAB\R2012b\extern\include\tmwtypes.h(821) : warning C4091: 'typedef ': ignorato a sinistra di 'wchar_t' quando non si dichiara alcuna variabile c:\program files\matlab\r2012b\extern\include\matrix.h(319) : error C4430: identificatore di tipo mancante, verr… utilizzato int. Nota: default-int non Š pi— supportato in C++ the content of my mexopts.bat is @echo off rem MSVC100OPTS.BAT rem rem Compile and link options used for building MEX-files rem using the Microsoft Visual C++ compiler version 10.0 rem rem $Revision: 1.1.6.4.2.1 $ $Date: 2012/07/12 13:53:59 $ rem Copyright 2007-2009 The MathWorks, Inc. rem rem StorageVersion: 1.0 rem C++keyFileName: MSVC100OPTS.BAT rem C++keyName: Microsoft Visual C++ 2010 rem C++keyManufacturer: Microsoft rem C++keyVersion: 10.0 rem C++keyLanguage: C++ rem C++keyLinkerName: Microsoft Visual C++ 2010 rem C++keyLinkerVersion: 10.0 rem rem ******************************************************************** rem General parameters rem ******************************************************************** set MATLAB=%MATLAB% set VSINSTALLDIR=c:\Program Files (x86)\Microsoft Visual Studio 10.0 set VCINSTALLDIR=%VSINSTALLDIR%\VC set OPENCVDIR=C:\OpenCV rem In this case, LINKERDIR is being used to specify the location of the SDK set LINKERDIR=c:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\ set PATH=%VCINSTALLDIR%\bin\amd64;%VCINSTALLDIR%\bin;%VCINSTALLDIR%\VCPackages;%VSINSTALLDIR%\Common7\IDE;%VSINSTALLDIR%\Common7\Tools;%LINKERDIR%\bin\x64;%LINKERDIR%\bin;%MATLAB_BIN%;%PATH% set INCLUDE=%OPENCVDIR%\build\include;%VCINSTALLDIR%\INCLUDE;%VCINSTALLDIR%\ATLMFC\INCLUDE;%LINKERDIR%\include;%INCLUDE% set LIB=%OPENCVDIR%\build\x64\vc10\lib;%VCINSTALLDIR%\LIB\amd64;%VCINSTALLDIR%\ATLMFC\LIB\amd64;%LINKERDIR%\lib\x64;%MATLAB%\extern\lib\win64;%LIB% set MW_TARGET_ARCH=win64 rem ******************************************************************** rem Compiler parameters rem ******************************************************************** set COMPILER=cl set COMPFLAGS=/c /GR /W3 /EHs /D_CRT_SECURE_NO_DEPRECATE /D_SCL_SECURE_NO_DEPRECATE /D_SECURE_SCL=0 /DMATLAB_MEX_FILE /nologo /MD set OPTIMFLAGS=/O2 /Oy- /DNDEBUG set DEBUGFLAGS=/Z7 set NAME_OBJECT=/Fo rem ******************************************************************** rem Linker parameters rem ******************************************************************** set LIBLOC=%MATLAB%\extern\lib\win64\microsoft set LINKER=link set LINKFLAGS=/dll /export:%ENTRYPOINT% /LIBPATH:"%LIBLOC%" libmx.lib libmex.lib libmat.lib /MACHINE:X64 kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib opencv_calib3d242.lib opencv_contrib242.lib opencv_core242.lib opencv_features2d242.lib opencv_flann242.lib opencv_gpu242.lib opencv_haartraining_engine.lib opencv_imgproc242.lib opencv_highgui242.lib opencv_legacy242.lib opencv_ml242.lib opencv_nonfree242.lib opencv_objdetect242.lib opencv_photo242.lib opencv_stitching242.lib opencv_ts242.lib opencv_video242.lib opencv_videostab242.lib /nologo /manifest /incremental:NO /implib:"%LIB_NAME%.x" /MAP:"%OUTDIR%%MEX_NAME%%MEX_EXT%.map" set LINKOPTIMFLAGS= set LINKDEBUGFLAGS=/debug /PDB:"%OUTDIR%%MEX_NAME%%MEX_EXT%.pdb" set LINK_FILE= set LINK_LIB= set NAME_OUTPUT=/out:"%OUTDIR%%MEX_NAME%%MEX_EXT%" set RSP_FILE_INDICATOR=@ rem ******************************************************************** rem Resource compiler parameters rem ******************************************************************** set RC_COMPILER=rc /fo "%OUTDIR%mexversion.res" set RC_LINKER= set POSTLINK_CMDS=del "%LIB_NAME%.x" "%LIB_NAME%.exp" set POSTLINK_CMDS1=mt -outputresource:"%OUTDIR%%MEX_NAME%%MEX_EXT%;2" -manifest "%OUTDIR%%MEX_NAME%%MEX_EXT%.manifest" set POSTLINK_CMDS2=del "%OUTDIR%%MEX_NAME%%MEX_EXT%.manifest" set POSTLINK_CMDS3=del "%OUTDIR%%MEX_NAME%%MEX_EXT%.map"

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  • C++ vs Matlab vs Python as a main language for Computer Vision Research

    - by Hough
    Hi all, Firstly, sorry for a somewhat long question but I think that many people are in the same situation as me and hopefully they can also gain some benefit from this. I'll be starting my PhD very soon which involves the fields of computer vision, pattern recognition and machine learning. Currently, I'm using opencv (2.1) C++ interface and I especially like its powerful Mat class and the overloaded operations available for matrix and image operations and seamless transformations. I've also tried (and implemented many small vision projects) using opencv python interface (new bindings; opencv 2.1) and I really enjoy python's ability to integrate opencv, numpy, scipy and matplotlib. But recently, I went back to opencv C++ interface because I felt that the official python new bindings were not stable enough and no overloaded operations are available for matrices and images, not to mention the lack of machine learning modules and slow speeds in certain operations. I've also used Matlab extensively in the past and although I've used mex files and other means to speed up the program, I just felt that Matlab's performance was inadequate for real-time vision tasks, be it for fast prototyping or not. When the project becomes larger and larger, many tasks have to be re-written in C and compiled into Mex files increasingly and Matlab becomes nothing more than a glue language. Here comes the sub-questions: For carrying out research in these fields (machine learning, vision, pattern recognition), what is your main or ideal programming language for rapid prototyping of ideas and testing algorithms contained in papers? For computer vision research work, can you list down the pros and cons of using the following languages? C++ (with opencv + gsl + svmlib + other libraries) vs Matlab (with all its toolboxes) vs python (with the imcomplete opencv bindings + numpy + scipy + matplotlib). Are there computer vision PhD/postgrad students here who are using only C++ (with all its availabe libraries including opencv) without even needing to resort to Matlab or python? In other words, given the current existing computer vision or machine learning libraries, is C++ alone sufficient for fast prototyping of ideas? If you're currently using Java or C# for your research, can you list down the reasons why they should be used and how they compare to other languages in terms of available libraries? What is the de facto vision/machine learning programming language and its associated libraries used in your research group? Thanks in advance. Edit: As suggested, I've opened the question to both academic and non-academic computer vision/machine learning/pattern recognition researchers and groups.

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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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  • Corner Cases, Unexpected and Unusual Matlab

    - by Mikhail
    Over the years, reading others code, I encountered and collected some examples of Matlab syntax which can be at first unusual and counterintuitive. Please, feel free to comment or complement this list. I verified it r2006a. set([], 'Background:Color','red') Matlab is very forgiving sometimes. In this case, setting properties to an array of objects works also with nonsense properties, at least when the array is empty. myArray([1,round(end/2)]) This use of end keyword may seem unclean but is sometimes very handy instead of using length(myArray). any([]) ~= all([]) Surprisigly any([]) returns false and all([]) returns true. And I always thought that all is stronger then any. EDIT: with not empty argument all() returns true for a subset of values for which any() returns true (e.g. truth table). This means that any() false implies all() false. This simple rule is being violated by Matlab with [] as argument. Loren also blogged about it. Select(Range(ExcelComObj)) Procedural style COM object method dispatch. Do not wonder that exist('Select') returns zero! [myString, myCell] Matlab makes in this case an implicit cast of string variable myString to cell type {myString}. It works, also if I would not expect it to do so. [double(1.8), uint8(123)] => 2 123 Another cast example. Everybody would probably expect uint8 value being cast to double but Mathworks have another opinion. a = 5; b = a(); It looks silly but you can call a variable with round brackets. Actually it makes sense because this way you can execute a function given its handle. a = {'aa', 'bb' 'cc', 'dd'}; Surprsisingly this code neither returns a vector nor rises an error but defins matrix, using just code layout. It is probably a relict from ancient times. set(hobj, {'BackgroundColor','ForegroundColor'},{'red','blue'}) This code does what you probably expect it to do. That function set accepts a struct as its second argument is a known fact and makes sense, and this sintax is just a cell2struct away. Equvalence rules are sometimes unexpected at first. For example 'A'==65 returns true (although for C-experts it is self-evident). About which further unexpected/unusual Matlab features are you aware?

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  • Why differs floating-point precision in C# when separated by parantheses and when separated by state

    - by Andreas Larsen
    I am aware of how floating point precision works in the regular cases, but I stumbled on an odd situation in my C# code. Why aren't result1 and result2 the exact same floating point value here? const float A; // Arbitrary value const float B; // Arbitrary value float result1 = (A*B)*dt; float result2 = (A*B); result2 *= dt; From this page I figured float arithmetic was left-associative and that this means values are evaluated and calculated in a left-to-right manner. The full source code involves XNA's Quaternions. I don't think it's relevant what my constants are and what the VectorHelper.AddPitchRollYaw() does. The test passes just fine if I calculate the delta pitch/roll/yaw angles in the same manner, but as the code is below it does not pass: X Expected: 0.275153548f But was: 0.275153786f [TestFixture] internal class QuaternionPrecisionTest { [Test] public void Test() { JoystickInput input; input.Pitch = 0.312312432f; input.Roll = 0.512312432f; input.Yaw = 0.912312432f; const float dt = 0.017001f; float pitchRate = input.Pitch * PhysicsConstants.MaxPitchRate; float rollRate = input.Roll * PhysicsConstants.MaxRollRate; float yawRate = input.Yaw * PhysicsConstants.MaxYawRate; Quaternion orient1 = Quaternion.Identity; Quaternion orient2 = Quaternion.Identity; for (int i = 0; i < 10000; i++) { float deltaPitch = (input.Pitch * PhysicsConstants.MaxPitchRate) * dt; float deltaRoll = (input.Roll * PhysicsConstants.MaxRollRate) * dt; float deltaYaw = (input.Yaw * PhysicsConstants.MaxYawRate) * dt; // Add deltas of pitch, roll and yaw to the rotation matrix orient1 = VectorHelper.AddPitchRollYaw( orient1, deltaPitch, deltaRoll, deltaYaw); deltaPitch = pitchRate * dt; deltaRoll = rollRate * dt; deltaYaw = yawRate * dt; orient2 = VectorHelper.AddPitchRollYaw( orient2, deltaPitch, deltaRoll, deltaYaw); } Assert.AreEqual(orient1.X, orient2.X, "X"); Assert.AreEqual(orient1.Y, orient2.Y, "Y"); Assert.AreEqual(orient1.Z, orient2.Z, "Z"); Assert.AreEqual(orient1.W, orient2.W, "W"); } } Granted, the error is small and only presents itself after a large number of iterations, but it has caused me some great headackes.

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  • OpenGL 2D Texture Mapping problem.

    - by gutsblow
    Hi there, I am relatively new to OpenGL and I am having some issues when I am rendering an image as a texture for a QUAD which is as the same size of the image. Here is my code. I would be very grateful if someone helps me to solve this problem. The image appears way smaller and is squished. (BTW, the image dimensions are 500x375). glGenTextures( 1, &S_GLator_InputFrameTextureIDSu ); glBindTexture(GL_TEXTURE_2D, S_GLator_InputFrameTextureIDSu); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP); glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); glTexImage2D( GL_TEXTURE_2D, 0, 4, S_GLator_EffectCommonData.mRenderBufferWidthSu, S_GLator_EffectCommonData.mRenderBufferHeightSu, 0, GL_RGBA, GL_UNSIGNED_BYTE, dataP); glBindTexture(GL_TEXTURE_2D, S_GLator_InputFrameTextureIDSu); glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, S_GLator_EffectCommonData.mRenderBufferWidthSu, S_GLator_EffectCommonData.mRenderBufferHeightSu, GL_RGBA, GL_UNSIGNED_BYTE, bufferP); //set the matrix modes glMatrixMode( GL_PROJECTION ); glLoadIdentity(); //gluPerspective( 45.0, (GLdouble)widthL / heightL, 0.1, 100.0 ); glOrtho (0, 1, 0, 1, -1, 1); // Set up the frame-buffer object just like a window. glViewport( 0, 0, widthL, heightL ); glDisable(GL_DEPTH_TEST); glClearColor( 0.0f, 0.0f, 0.0f, 0.0f ); glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); glMatrixMode( GL_MODELVIEW ); glLoadIdentity(); glBindTexture( GL_TEXTURE_2D, S_GLator_InputFrameTextureIDSu ); //Render the geometry to the frame-buffer object glBegin(GL_QUADS); //input frame glColor4f(1.f,1.f,1.f,1.f); glTexCoord2f(0.0f,0.0f); glVertex3f(0.f ,0.f ,0.0f); glTexCoord2f(1.0f,0.0f); glVertex3f(1.f ,0.f,0.0f); glTexCoord2f(1.0f,1.f); glVertex3f(1.f ,1.f,0.0f); glTexCoord2f(0.0f,1.f); glVertex3f(0.f ,1.f,0.0f); glEnd();

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  • How to convert a 32bpp image to an indexed format?

    - by Ed Swangren
    So here are the details (I am using C# BTW): I receive a 32bpp image (JPEG compressed) from a server. At some point, I would like to use the Palette property of a bitmap to color over-saturated pixels (brightness 240) red. To do so, I need to get the image into an indexed format. I have tried converting the image to a GIF, but I get quality loss. I have tried creating a new bitmap in an index format by these methods: // causes a "Parameter not valid" error Bitmap indexed = new Bitmap(orig.Width, orig.Height, PixelFormat.Indexed) // no error, but the resulting image is black due to information loss I assume Bitmap indexed = new Bitmap(orig.Width, orig.Height, PixelFormat.Format8bppIndexed) I am at a loss now. The data in this image is changed constantly by the user, so I don't want to manually set pixels that have a brightness 240 if I can avoid it. If I can set the palette once when the image is created, my work is done. If I am going about this the wrong way to begin with please let me know. EDIT: Thanks guys, here is some more detail on what I am attempting to accomplish. We are scanning a tissue slide at high resolution (pathology application). I write the interface to the actual scanner. We use a line-scan camera. To test the line rate of the camera, the user scans a very small portion and looks at the image. The image is displayed next to a track bar. When the user moves the track bar (adjusting line rate), I change the overall intensity of the image in an attempt to model what it would look like at the new line rate. I do this using an ImageAttributes and ColorMatrix object currently. When the user adjusts the track bar, I adjust the matrix. This does not give me per pixel information, but the performance is very nice. I could use LockBits and some unsafe code here, but I would rather not rewrite it if possible. When the new image is created, I would like for all pixels with a brightness value of 240 to be colored red. I was thinking that defining a palette for the bitmap up front would be a clean way of doing this.

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  • Model Fit of Binary GLM with more than 1 or 2 predictors

    - by Salmo salar
    I am trying to predict a binary GLM with multiple predictors. I can do it fine with one predictor variable however struggle when I use multiple Sample data: structure(list(attempt = structure(c(1L, 2L, 1L, 2L, 1L, 1L, 1L, 2L, 1L, 2L, 1L, 1L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 1L, 1L, 1L, 2L, 1L, 2L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 2L, 1L, 1L, 1L, 2L, 1L, 1L, 2L, 1L, 1L, 2L, 1L, 2L, 1L, 1L, 2L, 1L, 2L), .Label = c("1", "2"), class = "factor"), searchtime = c(137, 90, 164, 32, 39, 30, 197, 308, 172, 48, 867, 117, 63, 1345, 38, 122, 226, 397, 0, 106, 259, 220, 170, 102, 46, 327, 8, 10, 23, 108, 315, 318, 70, 646, 69, 97, 117, 45, 31, 64, 125, 17, 240, 63, 549, 1651, 233, 406, 334, 168, 127, 47, 881), mean.search.flow = c(15.97766667, 14.226, 17.15724762, 14.7465, 39.579, 23.355, 110.2926923, 71.95709524, 72.73666667, 32.37466667, 50.34905172, 27.98471429, 49.244, 109.1759778, 77.71733333, 37.446875, 101.23875, 67.78534615, 21.359, 36.54257143, 34.13961111, 64.35253333, 80.98554545, 61.50857143, 48.983, 63.81072727, 26.105, 46.783, 23.0605, 33.61557143, 46.31042857, 62.37061905, 12.565, 42.31983721, 15.3982, 14.49625, 23.77425, 25.626, 74.62485714, 170.1547778, 50.67125, 48.098, 66.83644444, 76.564875, 80.63189189, 136.0573243, 136.3484, 86.68688889, 34.82169565, 70.00415385, 64.67233333, 81.72766667, 57.74522034), Pass = structure(c(1L, 2L, 1L, 2L, 2L, 2L, 1L, 1L, 1L, 2L, 2L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 2L, 2L, 2L, 1L, 1L, 1L, 2L, 2L, 1L, 2L, 2L, 2L, 2L, 2L, 1L, 2L, 1L, 1L, 2L, 1L, 1L, 1L, 2L, 1L, 2L, 2L, 1L, 2L, 1L, 2L, 2L, 1L, 2L, 1L, 2L), .Label = c("0", "1"), class = "factor")), .Names = c("attempt", "searchtime", "mean.search.flow", "Pass"), class = "data.frame", row.names = c(1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 12L, 13L, 14L, 15L, 16L, 17L, 18L, 19L, 20L, 21L, 22L, 23L, 24L, 25L, 26L, 28L, 29L, 30L, 31L, 32L, 33L, 34L, 35L, 36L, 37L, 38L, 39L, 40L, 50L, 51L, 53L, 54L, 60L, 61L, 62L, 63L, 64L, 65L, 66L, 67L, 68L, 69L, 70L, 71L, 72L)) First model with single predictor M2 <- glm(Pass ~ searchtime, data = DF3, family = binomial) summary(M2) drop1(M2, test = "Chi") Plot works fine P1 <- predict(M2, newdata = MyData, type = "link", se = TRUE) plot(x=MyData$searchtime, exp(P1$fit) / (1+exp(P1$fit)), type = "l", ylim = c(0,1), xlab = "search time", ylab = "pobability of passage") lines(MyData$searchtime, exp(P1$fit+1.96*P1$se.fit)/ (1 + exp(P1$fit + 1.96 * P1$se.fit)), lty = 2) lines(MyData$searchtime, exp(P1$fit-1.96*P1$se.fit)/ (1 + exp(P1$fit - 1.96 * P1$se.fit)), lty = 2) points(DF3$searchtime, DF3$Search.and.pass) Second model M2a <- glm(Pass ~ searchtime + mean.search.flow+ attempt, data = DF3, family = binomial) summary(M2a) drop1(M2a, test = "Chi") How do I plot this with "dummy" data? I have tried along the lines of Model.matrix and expand.grid, as you would do with glmer, but fail straight away due to the two categorical variables along with factor(attempt)

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  • Android - OPENGL cube is NOT in the display

    - by Marc Ortiz
    I'm trying to display a square on my display and i can't. Whats my problem? How can I display it on the screen (center of the screen)? I let my code below! Here's my render class: public class GLRenderEx implements Renderer { private GLCube cube; Context c; GLCube quad; // ( NEW ) // Constructor public GLRenderEx(Context context) { // Set up the data-array buffers for these shapes ( NEW ) quad = new GLCube(); // ( NEW ) } // Call back when the surface is first created or re-created. @Override public void onSurfaceCreated(GL10 gl, EGLConfig config) { // NO CHANGE - SKIP } // Call back after onSurfaceCreated() or whenever the window's size changes. @Override public void onSurfaceChanged(GL10 gl, int width, int height) { // NO CHANGE - SKIP } // Call back to draw the current frame. @Override public void onDrawFrame(GL10 gl) { // Clear color and depth buffers using clear-values set earlier gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT); gl.glLoadIdentity(); // Reset model-view matrix ( NEW ) gl.glTranslatef(-1.5f, 0.0f, -6.0f); // Translate left and into the // screen ( NEW ) // Translate right, relative to the previous translation ( NEW ) gl.glTranslatef(3.0f, 0.0f, 0.0f); quad.draw(gl); // Draw quad ( NEW ) } } And here is my square class: public class GLCube { private FloatBuffer vertexBuffer; // Buffer for vertex-array private float[] vertices = { // Vertices for the square -1.0f, -1.0f, 0.0f, // 0. left-bottom 1.0f, -1.0f, 0.0f, // 1. right-bottom -1.0f, 1.0f, 0.0f, // 2. left-top 1.0f, 1.0f, 0.0f // 3. right-top }; // Constructor - Setup the vertex buffer public GLCube() { // Setup vertex array buffer. Vertices in float. A float has 4 bytes ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length * 4); vbb.order(ByteOrder.nativeOrder()); // Use native byte order vertexBuffer = vbb.asFloatBuffer(); // Convert from byte to float vertexBuffer.put(vertices); // Copy data into buffer vertexBuffer.position(0); // Rewind } // Render the shape public void draw(GL10 gl) { // Enable vertex-array and define its buffer gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer); // Draw the primitives from the vertex-array directly gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, vertices.length / 3); gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); } } Thanks!!

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  • Android - Transforming widgets within transformed widgets and the resulting usability issues.

    - by Ben Rose
    Hello. I'm new to Android application development and I'm currently experimenting with various UI ideas. In the image below, you can see a vertically scrolling list of horizontally scrolling galleries (and also textviews as you can see). I'm also doing some matrix and camera transformations which I will come to in a minute. For the background of the list elements, I use green. Blue is the background of the galleries, and red is the background for the images. These are just for my benefit of learning. The galleries being used are extended classes where I overrode the drawChild method to perform a canvas scale operation in order for the image closest to the center (width) to be larger than the others. The list view going vertically, I overrode the drawChild method and used the camera rotations from lack of depth dimension in the canvas functionality. The items in the list are scaled down and rotated relative to their position's proximity to the center (height). I understood that scrolling and clicking would not necessarily follow along with the image transforms, but it appears as though the parent Gallery class's drawing is constrained to the original coordinates as well (see photo below). I would love to hear any insight any of you have regarding how I can change the coordinates of the galleries in what is rendered via gallery scroll and the touch responsiveness of said gallery. Images in the gallery are not same dimensions, so don't let that throw you in looking at the image below Thanks in advance! Ben link to image (could not embed) -- Update: I was using my test application UI and noticed that when I got the UI to the point of the linked image and then I touched the top portion of the next row in the list, the gallery updated to display the proper representation. So, I added a call to clearFocus() in the drawChild method and that resulted in more accurate drawing. It does seem a tad slower, and since I'm on the Incredible, I'm worried it is a bloated solution. In any event, I would still appreciate any thoughts you have regarding the best way to have the views display properly and how to translate the touch events in the gallery's new displayed area to its touchable coordinates so that scrolling on the actual images works when the gallery has moved. Thanks!

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  • java quaternion 3D rotation implementation

    - by MRM
    I made a method to rotate a list of points using quaternions, but all i get back as output is the same list i gave to rotate on. Maybe i did not understood corectly the math for 3d rotations or my code is not implemented the right way, could you give me a hand? This is the method i use: public static ArrayList<Float> rotation3D(ArrayList<Float> points, double angle, int x, int y, int z) { ArrayList<Float> newpoints = points; for (int i=0;i<points.size();i+=3) { float x_old = points.get(i).floatValue(); float y_old = points.get(i+1).floatValue(); float z_old = points.get(i+2).floatValue(); double[] initial = {1,0,0,0}; double[] total = new double[4]; double[] local = new double[4]; //components for local quaternion //w local[0] = Math.cos(0.5 * angle); //x local[1] = x * Math.sin(0.5 * angle); //y local[2] = y * Math.sin(0.5 * angle); //z local[3] = z * Math.sin(0.5 * angle); //components for final quaternion Q1*Q2 //w = w1w2 - x1x2 - y1y2 - z1z2 total[0] = local[0] * initial[0] - local[1] * initial[1] - local[2] * initial[2] - local[3] * initial[3]; //x = w1x2 + x1w2 + y1z2 - z1y2 total[1] = local[0] * initial[1] + local[1] * initial[0] + local[2] * initial[3] - local[3] * initial[2]; //y = w1y2 - x1z2 + y1w2 + z1x2 total[2] = local[0] * initial[2] - local[1] * initial[3] + local[2] * initial[0] + local[3] * initial[1]; //z = w1z2 + x1y2 - y1x2 + z1w2 total[3] = local[0] * initial[3] + local[1] * initial[2] - local[2] * initial[1] + local[3] * initial[0]; //new x,y,z of the 3d point using rotation matrix made from the final quaternion float x_new = (float)((1 - 2 * total[2] * total[2] - 2 * total[3] * total[3]) * x_old + (2 * total[1] * total[2] - 2 * total[0] * total[3]) * y_old + (2 * total[1] * total[3] + 2 * total[0] * total[2]) * z_old); float y_new = (float) ((2 * total[1] * total[2] + 2 * total[0] * total[3]) * x_old + (1 - 2 * total[1] * total[1] - 2 * total[3] * total[3]) * y_old + (2 * total[2] * total[3] + 2 * total[0] * total[1]) * z_old); float z_new = (float) ((2 * total[1] * total[3] - 2 * total[0] * total[2]) * x_old + (2 * total[2] * total[3] - 2 * total[0] * total[1]) * y_old + (1 - 2 * total[1] * total[1] - 2 * total[2] * total[2]) * z_old); newpoints.set(i, x_new); newpoints.set(i+1, y_new); newpoints.set(i+2, z_new); } return newpoints; } For rotation3D(points, 50, 0, 1, 0) where points is: 0.0, 0.0, -9.0; 0.0, 0.0, -11.0; 20.0, 0.0, -11.0; 20.0, 0.0, -9.0; i get back the same list.

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  • Open Cl.I just need to convert the code to using two work items in the for loop .Currentlly it uses one

    - by user1660282
    spmv_csr_scalar_kernel(const int num_rows , const int * ptr , const int * indices , const float * data , const float * x, float * y) { int row = get_global_id(0); if(row < num_rows) { float dot = 0; int row_start = ptr[row]; int row_end = ptr[row+1]; for (int jj = row_start; jj < row_end; jj++) { dot += data[jj] * x[indices[jj]]; } y[row] += dot; } } Above is the Open Cl code for multiplying a sparse matrix in CSR format with a Column vector.It uses one global work item per for loop.Can anybody help me in using two work items in each for loop.I am new to open cl and get a lot of issues if I modify even the smallest thing.Please help me.This a part of my project.I made it this parallel but I wanna make it more parallel.Please help me if you can.plzzzz A single work item executes the for loop from row_start to row_end.I want that this row or for loop is further divided into two parts each executed by a single work item.How do I go on accomplishing that? This is what I could come up with but its returning the wrong output.plzz help __kernel void mykernel(__global int* colvector,__global int* val,__global int* result,__global int* index,__global int* rowptr,__global int* sync) { __global int vals[8]={0,0,0,0,0,0,0,0}; for(int i=0;i<4;i++) { result[i]=0; } barrier(CLK_GLOBAL_MEM_FENCE); int thread_id=get_global_id(0); int warp_id=thread_id/2; int lane=(thread_id)&1; int row=warp_id; if(row<4) { int row_start = rowptr[row]; int row_end = rowptr[row+1]; vals[thread_id]=0; for (int i = row_start+lane; i<row_end; i+=2) { vals[thread_id]+=val[i]*colvector[index[i]]; } vals[thread_id]+=vals[thread_id+1]; if(lane==0){ result[row] += vals[thread_id]; } } }

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  • c++ class member functions selected by traits

    - by Jive Dadson
    I am reluctant to say I can't figure this out, but I can't figure this out. I've googled and searched stackoverflow, and come up empty. The abstract, and possibly overly vague form of the question is, how can I use the traits-pattern to instantiate non-virtual member functions? The question came up while modernizing a set of multivariate function optimizers that I wrote more than 10 years ago. The optimizers all operate by selecting a straight-line path through the parameter space away from the current best point (the "update"), then finding a better point on that line (the "line search"), then testing for the "done" condition, and if not done, iterating. There are different methods for doing the update, the line-search, and conceivably for the done test, and other things. Mix and match. Different update formulae require different state-variable data. For example, the LMQN update requires a vector, and the BFGS update requires a matrix. If evaluating gradients is cheap, the line-search should do so. If not, it should use function evaluations only. Some methods require more accurate line-searches than others. Those are just some examples. The original version instatiates several of the combinations by means of virtual functions. Some traits are selected by setting mode bits. Yuck. It would be trivial to define the traits with #define's and the member functions with #ifdef's and macros. But that's so twenty years ago. It bugs me that I cannot figure out a whiz-bang modern way. If there were only one trait that varied, I could use the curiously recurring template pattern. But I see no way to extend that to arbitrary combinations of traits. I tried doing it using boost::enable_if, etc.. The specialized state info was easy. I managed to get the functions done, but only by resorting to non-friend external functions that have the this-pointer as a parameter. I never even figured out how to make the functions friends, much less member functions. Perhaps tag-dispatch is the key. I haven't gotten very deeply into that. Surely it's possible, right? If so, what is best practice?

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  • Problem on a Floyd-Warshall implementation using c++

    - by Henrique
    I've got a assignment for my college, already implemented Dijkstra and Bellman-Ford sucessfully, but i'm on trouble on this one. Everything looks fine, but it's not giving me the correct answer. Here's the code: void FloydWarshall() { //Also assume that n is the number of vertices and edgeCost(i,i) = 0 int path[500][500]; /* A 2-dimensional matrix. At each step in the algorithm, path[i][j] is the shortest path from i to j using intermediate vertices (1..k-1). Each path[i][j] is initialized to edgeCost(i,j) or infinity if there is no edge between i and j. */ for(int i = 0 ; i <= nvertices ; i++) for(int j = 0 ; j <= nvertices ; j++) path[i][j] = INFINITY; for(int j = 0 ; j < narestas ; j++) //narestas = number of edges { path[arestas[j]->v1][arestas[j]->v2] = arestas[j]->peso; //peso = weight of the edge (aresta = edge) path[arestas[j]->v2][arestas[j]->v1] = arestas[j]->peso; } for(int i = 0 ; i <= nvertices ; i++) //path(i, i) = 0 path[i][i] = 0; //test print, it's working fine //printf("\n\n\nResultado FloydWarshall:\n"); //for(int i = 1 ; i <= nvertices ; i++) // printf("distancia ao vertice %d: %d\n", i, path[1][i]); //heres the problem, it messes up, and even a edge who costs 4, and the minimum is 4, it prints 2. //for k = 1 to n for(int k = 1 ; k <= nvertices ; k++) //for i = 1 to n for(int i = 1 ; i <= nvertices ; i++) //for j := 1 to n for(int j = 1 ; j <= nvertices ; j++) if(path[i][j] > path[i][k] + path[k][j]) path[i][j] = path[i][k] + path[k][j]; printf("\n\n\nResultado FloydWarshall:\n"); for(int i = 1 ; i <= nvertices ; i++) printf("distancia ao vertice %d: %d\n", i, path[1][i]); } im using this graph example i've made: 6 7 1 2 4 1 5 1 2 3 1 2 5 2 5 6 3 6 4 6 3 4 2 means we have 6 vertices (1 to 6), and 7 edges (1,2) with weight 4... etc.. If anyone need more info, i'm up to giving it, just tired of looking at this code and not finding an error.

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  • segmented reduction with scattered segments

    - by Christian Rau
    I got to solve a pretty standard problem on the GPU, but I'm quite new to practical GPGPU, so I'm looking for ideas to approach this problem. I have many points in 3-space which are assigned to a very small number of groups (each point belongs to one group), specifically 15 in this case (doesn't ever change). Now I want to compute the mean and covariance matrix of all the groups. So on the CPU it's roughly the same as: for each point p { mean[p.group] += p.pos; covariance[p.group] += p.pos * p.pos; ++count[p.group]; } for each group g { mean[g] /= count[g]; covariance[g] = covariance[g]/count[g] - mean[g]*mean[g]; } Since the number of groups is extremely small, the last step can be done on the CPU (I need those values on the CPU, anyway). The first step is actually just a segmented reduction, but with the segments scattered around. So the first idea I came up with, was to first sort the points by their groups. I thought about a simple bucket sort using atomic_inc to compute bucket sizes and per-point relocation indices (got a better idea for sorting?, atomics may not be the best idea). After that they're sorted by groups and I could possibly come up with an adaption of the segmented scan algorithms presented here. But in this special case, I got a very large amount of data per point (9-10 floats, maybe even doubles if the need arises), so the standard algorithms using a shared memory element per thread and a thread per point might make problems regarding per-multiprocessor resources as shared memory or registers (Ok, much more on compute capability 1.x than 2.x, but still). Due to the very small and constant number of groups I thought there might be better approaches. Maybe there are already existing ideas suited for these specific properties of such a standard problem. Or maybe my general approach isn't that bad and you got ideas for improving the individual steps, like a good sorting algorithm suited for a very small number of keys or some segmented reduction algorithm minimizing shared memory/register usage. I'm looking for general approaches and don't want to use external libraries. FWIW I'm using OpenCL, but it shouldn't really matter as the general concepts of GPU computing don't really differ over the major frameworks.

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  • How do I stack images to simulate depth using Core Animation?

    - by Jeffrey Berthiaume
    I have a series of UIImages with which I need to simulate depth. I can't use scaling because I need to be able to rotate the parent view, and the images should look like they're stacked visibly in front of each other, not on the same plane. I made a new ViewController-based project and put this in the viewDidLoad (as well as attached three 120x120 pixel images named 1.png, 2.png, and 3.png): - (void)viewDidLoad { // display image 3 UIImageView *three = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"3.png"]]; three.center = CGPointMake(160 + 60, 240 - 60); [self.view addSubview:three]; // rotate image 3 around the z axis // THIS IS INCORRECT CATransform3D theTransform = three.layer.transform; theTransform.m34 = 1.0 / -1000; three.layer.transform = theTransform; // display image 2 UIImageView *two = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"2.png"]]; two.center = CGPointMake(160, 240); [self.view addSubview:two]; // display image 1 UIImageView *one = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"1.png"]]; one.center = CGPointMake(160 - 60, 240 + 60); [self.view addSubview:one]; // rotate image 3 around the z axis // THIS IS INCORRECT theTransform = one.layer.transform; theTransform.m34 = 1.0 / 1000; one.layer.transform = theTransform; // release the images [one release]; [two release]; [three release]; // rotate the parent view around the y axis theTransform = self.view.layer.transform; theTransform.m14 = 1.0 / -500; self.view.layer.transform = theTransform; [super viewDidLoad]; } I have very specific reasons why I'm not using an EAGLView and why I'm not loading the images as CALayers (i.e. why I'm using UIImageViews for each one). This is just a quick demo that I can use to work out exactly what I need in my parent application. Is there some matrix way to translate these 2d images along the z-axis so they will look like what I'm trying to represent? I've gone through the other StackOverflow articles as well as the Wikipedia references, and have not found what I'm looking for -- although I might not necessarily be using the right terms for what I'm trying to do.

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  • Mult-line Svg tooltip

    - by John Vaughan
    I have created numerous polygon shapes in SVG format. and grouped them together. When the user hovers over the group a tooltip box appear. I have used ecmascript. What i am looking to do is make the tooltip box a multiline box. Any ideas how to do this? <script type="text/ecmascript"> <![CDATA[ function init(evt) { if ( window.svgDocument == null ) { svgDocument = evt.target.ownerDocument; } tooltip = svgDocument.getElementById('tooltip'); tooltip_bg = svgDocument.getElementById('tooltip_bg'); } function ShowTooltip(evt, mouseovertext) { tooltip.setAttributeNS(null,"x",evt.clientX+17); tooltip.setAttributeNS(null,"y",evt.clientY+14); tooltip.firstChild.data = mouseovertext; tooltip.setAttributeNS(null,"visibility","visible"); length = tooltip.getComputedTextLength(); tooltip_bg.setAttributeNS(null,"width",length+8); tooltip_bg.setAttributeNS(null,"x",evt.clientX+14); tooltip_bg.setAttributeNS(null,"y",evt.clientY+1); tooltip_bg.setAttributeNS(null,"visibility","visibile"); } function HideTooltip(evt) { tooltip.setAttributeNS(null,"visibility","hidden"); tooltip_bg.setAttributeNS(null,"visibility","hidden"); } ]]> </script> <SVG> <g onmousemove="ShowTooltip(evt, 'GHANA 2000')" onmouseout="HideTooltip(evt)"> <path fill="#EEEEEE" d="M250,0c47,0,85.183,10.506,125,33.494L250,250V0z"/> <path id="score" d="M250,57c36.284,0,65.761,8.11,96.5,25.857L250,250V57z"/> <path fill="none" stroke="#FFFFFF" stroke-width="2" stroke-miterlimit="10" d="M250,0c47,0,85.183,10.506,125,33.494L250,250V0z"/> <text transform="matrix(1 0 0 1 283.9883 92.0024)" fill="#FFFFFF" font-family="'WalkwayBlack'" font-size="16">62</text> </g> <rect class="tooltip_bg" id="tooltip_bg" x="0" y="0" width="55" height="17" visibility="hidden"/> <text class="tooltip" id="tooltip" x="0" y="0" visibility="hidden">Tooltip</text> <SVG>

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  • c++ class member functions instatiated by traits

    - by Jive Dadson
    I am reluctant to say I can't figure this out, but I can't figure this out. I've googled and searched stackoverflow, and come up empty. The abstract, and possibly overly vague form of the question is, how can I use the traits-pattern to instantiate non-virtual member functions? The question came up while modernizing a set of multivariate function optimizers that I wrote more than 10 years ago. The optimizers all operate by selecting a straight-line path through the parameter space away from the current best point (the "update"), then finding a better point on that line (the "line search"), then testing for the "done" condition, and if not done, iterating. There are different methods for doing the update, the line-search, and conceivably for the done test, and other things. Mix and match. Different update formulae require different state-variable data. For example, the LMQN update requires a vector, and the BFGS update requires a matrix. If evaluating gradients is cheap, the line-search should do so. If not, it should use function evaluations only. Some methods require more accurate line-searches than others. Those are just some examples. The original version instantiates several of the combinations by means of virtual functions. Some traits are selected by setting mode bits that are tested at runtime. Yuck. It would be trivial to define the traits with #define's and the member functions with #ifdef's and macros. But that's so twenty years ago. It bugs me that I cannot figure out a whiz-bang modern way. If there were only one trait that varied, I could use the curiously recurring template pattern. But I see no way to extend that to arbitrary combinations of traits. I tried doing it using boost::enable_if, etc.. The specialized state info was easy. I managed to get the functions done, but only by resorting to non-friend external functions that have the this-pointer as a parameter. I never even figured out how to make the functions friends, much less member functions. The compiler (vc++ 2008) always complained that things didn't match. I would yell, "SFINAE, you moron!" but the moron is probably me. Perhaps tag-dispatch is the key. I haven't gotten very deeply into that. Surely it's possible, right? If so, what is best practice?

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  • How to set background in OpenGL captured image from OpenCV

    - by user325487
    Hey All, i'm relatively new to Artoolkitplus and openGL i'm having a tough time getting the image i capture through openCV to be set as the background image in OpenGL ... I also cannot convert the image i take through the camera using opencv to be scaled to 320x280 from 640x480 .. i also have to save my image and load if for things to work... here's my code //////////// int findMarker() { IplImage* image = cvQueryFrame( capture ); if( !capture ) { fprintf( stderr, "ERROR: capture is NULL \n" ); getchar(); return -1; } if( !image ) { fprintf( stderr, "ERROR: frame is null...\n" ); getchar(); } //cvShowImage( "Capture", frame ); //image = cvCloneImage( frame ); try{ if(!cvSaveImage("immagineTmp.jpg",image)) printf("Could not save\n"); } catch(void*) {} image = cvLoadImage("immagineTmp.jpg", 1); cvShowImage( "Image", image ); glLoadIdentity(); ////////////// glDisable(GL_DEPTH_TEST); glOrtho(0,640,0,480,-1,1); glGenTextures(1, &bgid); glBindTexture(GL_TEXTURE_2D, bgid); // Create Linear Filtered Texture glBindTexture(GL_TEXTURE_2D, bgid); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); glTexImage2D(GL_TEXTURE_2D, 0, 3, image-width, image-height, 0, GL_RGB, GL_UNSIGNED_BYTE, image-imageData); glBindTexture(GL_TEXTURE_2D, bgid); glBegin(GL_QUADS); glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.2f, -1.0f, -2.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.2f, -1.0f, -2.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.2f, 1.0f, -2.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.2f, 1.0f, -2.0f); glEnd(); glEnable(GL_DEPTH_TEST); glLoadIdentity(); //////////// // do the OpenGL camera setup glMatrixMode(GL_PROJECTION); glLoadMatrixf(tracker-getProjectionMatrix()); int markerId = tracker-calc((unsigned char *)(image-imageData)); float conf = tracker-getConfidence(); // use the result of calc() to setup the OpenGL transformation glMatrixMode(GL_MODELVIEW); glLoadMatrixf(tracker-getModelViewMatrix()); if(markerId!=-1) { printf("\n\nFound marker %d (confidence %d%%)\n\nPose-Matrix:\n ", markerId, (int(conf*100.0f))); for(int i=0; i<16; i++) printf("%.2f %s", tracker-getModelViewMatrix()[i], (i%4==3)?"\n " : ""); } cvReleaseImage(&image); return 0; }

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