Search Results

Search found 47301 results on 1893 pages for 'system matrix'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 35/1893 | < Previous Page | 31 32 33 34 35 36 37 38 39 40 41 42  | Next Page >

  • Matrix multiplication in java (RE-POST)

    - by Chapax
    Apologies for the re-post; the earlier time I'd posted I did not have all the details. My colleague, who quit the firm was a C# programmer, was forced to write Java code that involved (large, dense) matrix multiplication. He's coded his own DataTable class in Java, in order to be able to a) create indexes to sort and join with other DataTables b) do matrix multiplication. The code in its current form is NOT maintainable/extensible. I want to clean up the code, and thought using something like R within Java will help me focus on business logic rather than sorting, joining, matrix multiplication, etc. Plus, I'm very new to the concept of DataTable; I just want to replace the DataTable with 2D arrays, and let R handle the rest. (I currently do not know how to join 2 large datasets in java very efficiently Please let me know what you think. Also, are there any simple examples that I can take a look at?

    Read the article

  • Performance question: Inverting an array of pointers in-place vs array of values

    - by Anders
    The background for asking this question is that I am solving a linearized equation system (Ax=b), where A is a matrix (typically of dimension less than 100x100) and x and b are vectors. I am using a direct method, meaning that I first invert A, then find the solution by x=A^(-1)b. This step is repated in an iterative process until convergence. The way I'm doing it now, using a matrix library (MTL4): For every iteration I copy all coeffiecients of A (values) in to the matrix object, then invert. This the easiest and safest option. Using an array of pointers instead: For my particular case, the coefficients of A happen to be updated between each iteration. These coefficients are stored in different variables (some are arrays, some are not). Would there be a potential for performance gain if I set up A as an array containing pointers to these coefficient variables, then inverting A in-place? The nice thing about the last option is that once I have set up the pointers in A before the first iteration, I would not need to copy any values between successive iterations. The values which are pointed to in A would automatically be updated between iterations. So the performance question boils down to this, as I see it: - The matrix inversion process takes roughly the same amount of time, assuming de-referencing of pointers is non-expensive. - The array of pointers does not need the extra memory for matrix A containing values. - The array of pointers option does not have to copy all NxN values of A between each iteration. - The values that are pointed to the array of pointers option are generally NOT ordered in memory. Hopefully, all values lie relatively close in memory, but *A[0][1] is generally not next to *A[0][0] etc. Any comments to this? Will the last remark affect performance negatively, thus weighing up for the positive performance effects?

    Read the article

  • Rating System Database Structure

    - by Harsha M V
    I have two entity groups. Restaurants and Users. Restaurants can be rated (1-5) by users. And rating fromeach user should be retrievable. Resturant(id, name, ..... , total_number_of_votes, total_voting_points ) User (id, name ...... ) Rating (id, restaurant_id, user_id, rating_value) Do i need to store the avg value so that it need not be calculated every time ? which table is the best place to store avg_rating, total_no_of_votes, total_voting_points ?

    Read the article

  • .Net System.Mail.Message adding multiple "To" addresses

    - by Matt Dawdy
    I just hit something I think is inconsistent, and wanted to see if I'm doing something wrong, if I'm an idiot, or... MailMessage msg = new MailMessage(); msg.To.Add("[email protected]"); msg.To.Add("[email protected]"); msg.To.Add("[email protected]"); msg.To.Add("[email protected]"); Really only sends this email to 1 person, the last one. To add multiples I have to do this: msg.To.Add("[email protected],[email protected],[email protected],[email protected]"); I don't get it. I thought I was adding multiple people to the "To" address collection, but what I was doing was replacing it. I think I just realized my error -- to add one item to the collection, use .To.Add(new MailAddress("[email protected]")) If you use just a string, it replaces everything it had in its list. Ugh. I'd consider this a rather large gotcha! Since I answered my own question, but I think this is of value to have in the stackoverflow archive, I'll still ask it. Maybe someone even has an idea of other traps that you can fall into.

    Read the article

  • Naive question of memory references in Operating system

    - by darkie15
    Hi All, I am learning memory references pertaining to Operating systems and don't seem to get to the crux of understanding it. For example, I am not able to visualize this scenario properly: "A 36 bit address employs both paging and segmentation. Both PTE and STE are 4 bytes each". How are they related? I can guess that this question might be too simple for many. But any help understanding the above basic concept would be appreciable. Regards, darkie15

    Read the article

  • C system calls open / read / write / close problem.

    - by Andrei Ciobanu
    Hello, given the following code (it's supposed to write "hellowolrd" in a "helloworld" file, and then read the text): #include <fcntl.h> #include <sys/types.h> #include <sys/stat.h> #define FNAME "helloworld" int main(){ int filedes, nbytes; char buf[128]; /* Creates a file */ if((filedes=open(FNAME, O_CREAT | O_EXCL | O_WRONLY | O_APPEND, S_IRUSR | S_IWUSR)) == -1){ write(2, "Error1\n", 7); } /* Writes hellow world to file */ if(write(filedes, FNAME, 10) != 10) write(2, "Error2\n", 7); /* Close file */ close(filedes); if((filedes = open(FNAME, O_RDONLY))==-1) write(2, "Error3\n", 7); /* Prints file contents on screen */ if((nbytes=read(filedes, buf, 128)) == -1) write(2, "Error4\n", 7); if(write(1, buf, nbytes) != nbytes) write(2, "Error5\n", 7); /* Close rile afte read */ close(filedes); return (0); } The first time i run the program, the output is: helloworld After that every time I to run the program, the output is: Error1 Error2 helloworld I don't understand why the text isn't appended, as I've specified the O_APPEND file. Is it because I've included O_CREAT ? It the file is already created, shouldn't O_CREAT be ignored ?

    Read the article

  • Undo button for System.Drawing?

    - by Tanner
    Hi guys, I am making a image editor kinda for own enjoyment and was wondering how could I make a undo button to undo the last paints I did? I want to know how I would about this, a tutorial or sample code would be nice or at least something pointing me in the right direction. Thanks!

    Read the article

  • Understanding The Convolution Matrix

    - by Ryan Naddy
    I am learning about the Convolution Matrix, and I understand how they work, but I don't understand how to know before hand what the output of a Matrix will look like. For example lets say I want to add a blur to an image, I could guess 10,000+ different combinations of numbers before I get the correct one. I do know though that this formula will give me a blur effect, but I have no idea why. float[] sharpen = new float[] { 1/9f, 1/9f, 1/9f, 1/9f, 1/9f, 1/9f, 1/9f, 1/9f, 1/9f }; Can anyone either explain to me how this works or point me to some article, that explains this? I would like to know before hand what a possible output of the matrix will be without guessing. Basically I would like to know why do we put that number in the filed, and why not some other number?

    Read the article

  • Multiplying two matrices from two text files with unknown dimensions

    - by wes schwertner
    This is my first post here. I've been working on this c++ question for a while now and have gotten nowhere. Maybe you guys can give me some hints to get me started. My program has to read two .txt files each containing one matrix. Then it has to multiply them and output it to another .txt file. My confusion here though is how the .txt files are setup and how to get the dimensions. Here is an example of matrix 1.txt. #ivalue #jvalue value 1 1 1.0 2 2 1 The dimension of the matrix is 2x2. 1.0 0 0 1 Before I can start multiplying these matrices I need to get the i and j value from the text file. The only way I have found out to do this is int main() { ifstream file("a.txt"); int numcol; float col; for(int x=0; x<3;x++) { file>>col; cout<<col; if(x==1) //grabs the number of columns numcol=col; } cout<<numcol; } The problem is I don't know how to get to the second line to read the number of rows. And on top of that I don't think this will give me accurate results for other matrices files. Let me know if anything is unclear. UPDATE Thanks! I got getline to work correctly. But now I am running into another problem. In matrix B it is setup like: #ivalue #jvalue Value 1 1 0.1 1 2 0.2 2 1 0.3 2 2 0.4 I need to let the program know that it needs to go down 4 lines, maybe even more (The matrices dimensions are unknown. My matrix B example is a 2x2, but it could be a 20x20). I have a while(!file.eof()) loop my program to let it loop until the end of file. I know I need a dynamic array for multiplying, but would I need one here also? #include <iostream> #include <fstream> using namespace std; int main() { ifstream file("a.txt"); //reads matrix A while(!file.eof()) { int temp; int numcol; string numrow; float row; float col; for(int x=0; x<3;x++) { file>>col; if(x==1) { numcol=col; //number of columns } } string test; getline(file, test); //next line to get rows for(int x=0; x<3; x++) { file>>test; if(x==1) { numrow=test; //sets number of rows } } cout<<numrow; cout<<numcol<<endl; } ifstream file1("b.txt"); //reads matrix 2 while(!file1.eof()) { int temp1; int numcol1; string numrow1; float row1; float col1; for(int x=0; x<2;x++) { file1>>col1; if(x==1) numcol1=col1; //sets number of columns } string test1; getline(file1, test1); //In matrix B there are four rows. getline(file1, test1); //These getlines go down a row. getline(file1, test1); //Need help here. for(int x=0; x<2; x++) { file1>>test1; if(x==1) numrow1=test1; } cout<<numrow1; cout<<numcol1<<endl; } }

    Read the article

  • Matlab: Randomize and Split

    - by Null-Hypothesis
    I have following data matrix in Matlab, I am trying to actually split this into multiple segments by passing a variable to a matlab function. But before splitting I would like to shuffle the matrix. The size of my matrix is 150X4 s.data 5.1000 3.5000 1.4000 0.2000 4.9000 3.0000 1.4000 0.2000 4.7000 3.2000 1.3000 0.2000 4.6000 3.1000 1.5000 0.2000 5.0000 3.6000 1.4000 0.2000 .. s = data: [150x4 double] labels: [150x1 double] Coming from R environment I find MatLab is very strange. Initially I thought the columns in matrix has a relationshop like in a R dataframe but thats wrong in my assumption.

    Read the article

  • Operating System Widget Side Project

    - by Calpis
    I want to start on a side project and here's my idea: Whenever the user's mouse is pressed down, I want a small ring around the cursor to show up. I'm mainly doing this to learn more about programming and get myself to think outside of work related materials. My questions are: 1) is there a good source I can reference to start a project that deals with something like this? 2) Is visual studio a sufficient software to create such an application? Or would I need some other tool to do this. 3) What language should I choose to do this task? Thanks in advance!

    Read the article

  • C++ template typedef

    - by Notinlist
    I have a class template<size_t N, size_t M> class Matrix { // .... }; I want to make a typedef which creates a Vector (column vector) which is equivalent to a Matrix with sizes N and 1. Something like that: typedef Matrix<N,1> Vector<N>; Which produces compile error. The following creates something similar, but not exactly what I want: template <int N> class Vector: public Matrix<N,1> { }; Is there a solution or a not too expensive workaround / best-practice for it? Thanks in advance!

    Read the article

  • write 2d array to a file in C (Operating system)

    - by Bobj-C
    Hello All, I used to use the code below to Write an 1D array to a File: FILE *fp; float floatValue[5] = { 1.1F, 2.2F, 3.3F, 4.4F, 5.5F }; int i; if((fp=fopen("test", "wb"))==NULL) { printf("Cannot open file.\n"); } if(fwrite(floatValue, sizeof(float), 5, fp) != 5) printf("File read error."); fclose(fp); /* read the values */ if((fp=fopen("test", "rb"))==NULL) { printf("Cannot open file.\n"); } if(fread(floatValue, sizeof(float), 5, fp) != 5) { if(feof(fp)) printf("Premature end of file."); else printf("File read error."); } fclose(fp); for(i=0; i<5; i++) printf("%f ", floatValue[i]); My question is if i want to write and read 2D array ??

    Read the article

  • How can i use the Orientation correct for images

    - by user3578109
    I´m learning android/java by myself @the moment and i have a problem with a part of my app i´m learning on. I made the code with help of the www and my problem is that if i open an image from the gallery it´s send to the edit activity but in the activity pictures what are made in portrait mode are displayed always wrong (90° to the right side).... The codes are Matrix private Bitmap rotateBitmapToOrientation(Bitmap b, int orientation){ Matrix matrix = new Matrix(); matrix.postRotate(orientation); Canvas offscreenCanvas = new Canvas(); offscreenCanvas.drawBitmap(b, matrix, null); return b; } and the other one @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); switch (requestCode) { case PICK_IMAGE_FROM_GALLERY: { if (resultCode == RESULT_OK) { Log.d(TAG, "Got Picture!"); Log.d(TAG,"File type - " + data.getType()); Uri photoUri = data.getData(); if (photoUri != null) { try { String[] filePathColumn = {MediaStore.Images.Media.DATA}; String[] orientationColumn = {MediaStore.Images.Media.ORIENTATION}; int orientation = -1; Cursor cursor = getContentResolver().query(photoUri, filePathColumn, null, null, null); cursor.moveToFirst(); int columnIndex = cursor.getColumnIndex(filePathColumn[0]); String filePath = cursor.getString(columnIndex); cursor.close(); cursor = getContentResolver().query(photoUri, orientationColumn, null, null, null); if(cursor != null && cursor.moveToFirst()){ orientation = cursor.getInt(cursor.getColumnIndex(orientationColumn[0])); } cursor.close(); HashMap<String, Integer> pRes = this.getImageResolutionSetting(); Bitmap shrunkenBitmap = FileUtilsHelper.shrinkBitmap(filePath, pRes.get("width"), pRes.get("height")); shrunkenBitmap = rotateBitmapToOrientation(shrunkenBitmap, orientation); String res = FileUtilsHelper.saveBitmapAsJpeg(shrunkenBitmap, this); Log.d(TAG,"File Path: " + res); shrunkenBitmap.recycle(); Intent editImage = new Intent(this, EditImage.class); editImage.addFlags(Intent.FLAG_ACTIVITY_FORWARD_RESULT); editImage.putExtra("stuff.path", res); startActivity(editImage); }catch(Exception e){ Toast.makeText(this, R.string.cant_save_image,Toast.LENGTH_SHORT).show(); } } } } break; } }} I don´t know what i´m doing wrong... I could really need a teacher on that :) Thx for your help dudes!!

    Read the article

  • C# - can you name a matrix with the contents of a string

    - by RHodgett
    Basically I have x amount of matrices I need to establish of y by y size. I was hoping to name the matrices: matrixnumber1 matrixnumber2..matrixnumbern I cannot use an array as its matrices I have to form. Is it possible to use a string to name a string (or a matrix in this case)? Thank you in advance for any help on this! for (int i = 1; i <= numberofmatricesrequired; i++) { string number = Convert.ToString(i); Matrix (matrixnumber+number) = new Matrix(matrixsize, matrixsize); }

    Read the article

  • SQLAuthority News – SQL Server 2008 R2 System Views Map

    - by pinaldave
    SQL Server 2008 R2 System Views Map is released. I am very proud that my organization (Solid Quality Mentors) is part of making this possible. This map shows the key system views included in SQL Server 2008 and 2008 R2, and the relationships between them. SQL Server 2008 R2 System Views Map Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: SQL, SQL Authority, SQL Documentation, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology

    Read the article

  • .NET Framework 4.0 mysteriously loses track of System.EnterpriseServices

    - by Lorin Thwaits
    The GAC in .NET 4.0 is cut into two parts now -- one half for .NET Framework 2.0 stuff, and the other for v4.0 stuff. When compiling any project, targeting .NET 2.0, 3.5, or what have you, this annoying error may pop up: Could not load file or assembly 'System.EnterpriseServices, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified. In that case, open a run box and perform this copy command: xcopy %ProgramFiles%\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0\System.EnterpriseServices.dll %windir%\Microsoft.NET\assembly\GAC_32\System.EnterpriseServices\v4.0_4.0.0.0__b03f5f7f11d50a3a /e This reconstructs the proper portion of the GAC for that one missing file.

    Read the article

  • Visual Studio confused when there are multiple system.web sections in your web.config

    - by Jeff Widmer
    I am trying to start debugging in Visual Studio for the website I am currently working on but Visual Studio is telling me that I have to enable debugging in the web.config to continue: But I clearly have debugging enabled: At first I chose the option to Modify the Web.config file to enable debugging but then I started receiving the following exception on my site: HTTP Error 500.19 - Internal Server Error The requested page cannot be accessed because the related configuration data for the page is invalid. Config section 'system.web/compilation' already defined. Sections must only appear once per config file. See the help topic <location> for exceptions   So what is going on here?  I already have debug=”true”, Visual Studio tells me I do not, and then when I give Visual Studio permission to fix the problem, I get a configuration error. Eventually I tracked it down to having two <system.web> sections. I had defined customErrors higher in the web.config: And then had a second system.web section with compilation debug=”true” further down in the web.config.  This is valid in the web.config and my site was not complaining but I guess Visual Studio does not know how to handle it and sees the first system.web, does not see the debug=”true” and thinks your site is not set up for debugging. To fix this so that Visual Studio was not going to complain, I removed the duplicate system.web declaration and moved the customErrors statement down.

    Read the article

  • SSIS Catalog, Windows updates and deployment failures due to System.Core mismatch

    - by jamiet
    This is a heads-up for anyone doing development on SSIS. On my current project where we are implementing a SQL Server Integration Services (SSIS) 2012 solution we recently encountered a situation where we were unable to deploy any of our projects even though we had successfully deployed in the past. Any attempt to use the deployment wizard resulted in this error dialog: The text of the error (for all you search engine crawlers out there) was: A .NET Framework error occurred during execution of user-defined routine or aggregate "create_key_information": System.IO.FileLoadException: Could not load file or assembly 'System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040) ---> System.IO.FileLoadException: The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040) System.IO.FileLoadException: System.IO.FileLoadException:     at Microsoft.SqlServer.IntegrationServices.Server.Security.CryptoGraphy.CreateSymmetricKey(String algorithm)    at Microsoft.SqlServer.IntegrationServices.Server.Security.CryptoGraphy.CreateKeyInformation(SqlString algorithmName, SqlBytes& key, SqlBytes& IV) . (Microsoft SQL Server, Error: 6522) After some investigation and a bit of back and forth with some very helpful members of the SSIS product team (hey Matt, Wee Hyong) it transpired that this was due to a .Net Framework fix that had been delivered via Windows Update. I took a look at the server update history and indeed there have been some recently applied .Net Framework updates: This fix had (in the words of Matt Masson) “somehow caused a mismatch on System.Core for SQLCLR” and, as you may know, SQLCLR is used heavily within the SSIS Catalog. The fix was pretty simple – restart SQL Server. This causes the assemblies to be upgraded automatically. If you are using Data Quality Services (DQS) you may have experienced similar problems which are documented at Upgrade SQLCLR Assemblies After .NET Framework Update. I am hoping the SSIS team will follow-up with a more thorough explanation on their blog soon. You DBAs out there may be questioning why Windows Update is set to automatically apply updates on our production servers. We’re checking that out with our hosting provider right now You have been warned! @Jamiet

    Read the article

  • Microsoft lance System Center : une plate-forme unique et complète pour l'administration systèmes

    Microsoft® System Center est une plate-forme unique et complète pour l'administration des postes de travail, des serveurs, des applications et des périphériques, en environnement physique ou virtuel. Citation: La gamme de produits System Center a pour but de simplifier les opérations et les changements, de réduire les durées de dépannage et d'améliorer les capacités de planification au sein de votre entreprise dans une optique de réduction des coûts. Optimisée pour une administration système dynamique, System Center vous aide à fournir le niv...

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 31 32 33 34 35 36 37 38 39 40 41 42  | Next Page >