Recursion with matrix parts

This is a discussion on Recursion with matrix parts within the C++ Programming forums, part of the General Programming Boards category; As a part of the project I'm working on, the input matrix needs to be deflated, meaning split into 2 ...

  1. #1
    Registered User
    Join Date
    Mar 2010
    Posts
    43

    Recursion with matrix parts

    As a part of the project I'm working on, the input matrix needs to be deflated, meaning split into 2 parts. These parts are the upper left and lower right portions of the original matrix, and certain operation needs to be performed there. When in the process of deflation(splitting) we encounter a 1x1` matrix, we should stop and print that matrix. Take a look at the following code:
    Code:
    void ImplicitQRdeflatedAll(Matrix Dmatrix, VecDouble& EigenValues) {
            if(Dmatrix.rowNo==1) {
             PrintMatrix(Dmatrix);
              return;
            } else {
                     for(int i=1;i<=20;i++) {
                     Dmatrix=forImplicitQR(Dmatrix);
                     if(i%3==0) {
                      int k=checkConvDominant(Dmatrix);
                     if(k!=-1) {
                        std::pair<Matrix, Matrix> myLRpair=deflate(Dmatrix, k);
                       ImplicitQRdeflatedAll(myLRpair.first, EigenValues);
                       ImplicitQRdeflatedAll(myLRpair.second, EigenValues);
                      return;
                    }
               }
           }
       }
    }
    The idea is to print out n(where n is the number of rows/columns of the input matrix) 1x1 matrices, but the code above sometimes reaches n print outs, but more frequently less than n printouts. Any idea why this happens? Thanks

  2. #2
    Registered User
    Join Date
    Mar 2010
    Posts
    43
    Note that the input is square symmetric matrix, so I should end up with n Eigenvalues.
    I've rewritten the code, in order to get what's going on more clearly:
    Code:
    void ImplicitQRdeflatedAllRAM(MatrixRAM Dmatrix);
    void splittingMethodRAM(MatrixRAM t1, MatrixRAM t2) {
          if(t1.rowNo==1 && t2.rowNo==1) {
    	    std::cout<<"Cond 1:"<<t1.mat[0]<<std::endl;
    	    std::cout<<"Cond 1:"<<t2.mat[0]<<std::endl;
          } else if (t1.rowNo==1 && t2.rowNo!=1) {
    	    std::cout<<"Cond 2:"<<t1.mat[0]<<std::endl;
    	    ImplicitQRdeflatedAllRAM(t2);
          } else if (t1.rowNo!=1 && t2.rowNo==1) {
    	    std::cout<<"Cond 3:"<<t2.mat[0]<<std::endl;
    	    ImplicitQRdeflatedAllRAM(t1);
          } else {
    	    ImplicitQRdeflatedAllRAM(t1);
    	    ImplicitQRdeflatedAllRAM(t2);
          }
    }
    void ImplicitQRdeflatedAllRAM(MatrixRAM Dmatrix) { 
      for(int i=1;i<=20;i++) {
              Dmatrix=forImplicitQR_RAM(Dmatrix);
              if(i%3==0) {
                  int k=checkConvDominantRAM(Dmatrix);
                  if(k!=-1) {
                       std::pair<MatrixRAM, MatrixRAM> myLRpair=deflateRAM(Dmatrix, k);
    		   displayMatrixRAM(myLRpair.first);
    		   displayMatrixRAM(myLRpair.second);
                       splittingMethodRAM(myLRpair.first, myLRpair.second);
    		   break;
                  }
              }
         }
    }
    This is the sample output (execution 1):
    Code:
    23.69576914
    
    -3.537866479 0.1513080256 -2.524960609e-16 -2.506805929e-16 -8.999473823e-17 -3.28069668e-17
    0.1513080256 -2.657773649 0.5516137251 1.034959735e-16 6.084075703e-17 7.224027212e-17
    -1.255177787e-17 0.5516137251 -2.593802287 0.3667046744 -7.525384817e-17 -1.058456459e-16
    -7.855743689e-18 3.002372497e-18 0.3667046744 -1.892084595 0.2455554104 9.020562075e-17
    -1.563849581e-18 -2.549194837e-17 2.35747981e-17 0.2455554104 -1.947101501 0.1002610174
    -5.210227644e-18 2.280112503e-17 -3.450402403e-17 1.387778781e-17 0.1002610174 -1.283769202
    
    Cond 2:23.69576914
    Note that the size of the second matrix is more than 1X1, and that ImplicitQRdeflatedAllRAM(t2); from the first else if statement should be executed(splitting further the matrix). However, the program stops here. But on some other execution, I get the following output:
    Code:
    23.69576914 
    
    -3.262118558 0.1637324253 6.68950829e-17 6.180268921e-17 4.243345686e-17 1.565355317e-17 
    0.1637324253 -3.087526486 0.6684337753 -3.071079334e-16 -1.512251779e-16 -5.584501028e-17 
    8.660922781e-19 0.6684337753 -2.435240634 0.2545919516 8.662132137e-17 2.839714523e-17    
    -3.568173353e-18 -3.450598481e-17 0.2545919516 -1.828971387 0.3103821624 -4.163336342e-17 
    -1.07389778e-17 2.661498469e-17 -3.28059203e-17 0.3103821624 -1.557021983 0.2934575252    
    -6.219060656e-18 1.853667482e-17 -1.385474889e-17 6.938893904e-18 0.2934575252 -1.687626971 
    
    Cond 2:23.69576914
    -3.543672409 0.1062454639 
    0.1062454639 -3.241790696 
    
    -2.219674091 0.02745130302 1.185696483e-16 1.870220652e-16 
    0.02745130302 -1.962574437 0.02332143798 -2.093120057e-16  
    -5.189155563e-18 0.02332143798 -1.685130584 0.001669833018 
    -1.084473558e-17 -5.393905808e-18 0.001669833018 -1.205663802 
    
    -2.221203145 -0.01894417801 -1.24367854e-16 
    -0.01894417801 -1.962220104 0.0147521074    
    5.090329784e-18 0.0147521074 -1.683960903   
    
    -1.205658762 
    
    Cond 3:-1.205658762
    -2.222568222 -0.002008037457 
    -0.002008037457 -1.961633638 
    
    -1.683182292
    
    Cond 3:-1.683182292
    -2.222580222
    
    -1.961621638
    
    Cond 1:-2.222580222
    Cond 1:-1.961621638
    Note that here the second matrix is of the same dimension as in the first output, but the program here continues with the execution. Any clues how to allow the program the complete execution?

Popular pages Recent additions subscribe to a feed

Similar Threads

  1. C - access violation
    By uber in forum C Programming
    Replies: 2
    Last Post: 07-08-2009, 01:30 PM
  2. Matrix Help
    By HelpmeMark in forum C++ Programming
    Replies: 27
    Last Post: 03-06-2008, 04:57 PM
  3. matrix program issue, recursion
    By sweener2001 in forum C Programming
    Replies: 1
    Last Post: 04-28-2005, 04:28 AM
  4. What is a matrix's purpose in OpenGL
    By jimboob in forum Game Programming
    Replies: 5
    Last Post: 11-13-2004, 11:19 PM

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21