Line data    Source code

       1             : /*
       2             :    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
       3             :    SLEPc - Scalable Library for Eigenvalue Problem Computations
       4             :    Copyright (c) 2002-, Universitat Politecnica de Valencia, Spain
       5             : 
       6             :    This file is part of SLEPc.
       7             :    SLEPc is distributed under a 2-clause BSD license (see LICENSE).
       8             :    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
       9             : */
      10             : 
      11             : static char help[] = "SVD via the cross-product matrix with a user-provided EPS.\n\n"
      12             :   "The command line options are:\n"
      13             :   "  -m <m>, where <m> = matrix rows.\n"
      14             :   "  -n <n>, where <n> = matrix columns (defaults to m+2).\n\n";
      15             : 
      16             : #include <slepcsvd.h>
      17             : 
      18             : /*
      19             :    This example computes the singular values of a rectangular bidiagonal matrix
      20             : 
      21             :               |  1  2                     |
      22             :               |     1  2                  |
      23             :               |        1  2               |
      24             :           A = |          .  .             |
      25             :               |             .  .          |
      26             :               |                1  2       |
      27             :               |                   1  2    |
      28             :  */
      29             : 
      30           2 : int main(int argc,char **argv)
      31             : {
      32           2 :   Mat            A;
      33           2 :   SVD            svd;
      34           2 :   EPS            eps;
      35           2 :   ST             st;
      36           2 :   KSP            ksp;
      37           2 :   PC             pc;
      38           2 :   PetscInt       m=20,n,Istart,Iend,i,col[2];
      39           2 :   PetscScalar    value[] = { 1, 2 };
      40           2 :   PetscBool      flg,expmat;
      41             : 
      42           2 :   PetscFunctionBeginUser;
      43           2 :   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
      44           2 :   PetscCall(PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL));
      45           2 :   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,&flg));
      46           2 :   if (!flg) n=m+2;
      47           2 :   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nRectangular bidiagonal matrix, m=%" PetscInt_FMT " n=%" PetscInt_FMT "\n\n",m,n));
      48             : 
      49             :   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      50             :         Generate the matrix
      51             :      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
      52             : 
      53           2 :   PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
      54           2 :   PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,m,n));
      55           2 :   PetscCall(MatSetFromOptions(A));
      56           2 :   PetscCall(MatGetOwnershipRange(A,&Istart,&Iend));
      57          42 :   for (i=Istart;i<Iend;i++) {
      58          40 :     col[0]=i; col[1]=i+1;
      59          40 :     if (i<n-1) PetscCall(MatSetValues(A,1,&i,2,col,value,INSERT_VALUES));
      60          40 :     else if (i==n-1) PetscCall(MatSetValue(A,i,col[0],value[0],INSERT_VALUES));
      61             :   }
      62           2 :   PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY));
      63           2 :   PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY));
      64             : 
      65             :   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      66             :         Create a standalone EPS with appropriate settings
      67             :      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
      68             : 
      69           2 :   PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));
      70           2 :   PetscCall(EPSGetST(eps,&st));
      71           2 :   PetscCall(STSetType(st,STSINVERT));
      72           2 :   PetscCall(STGetKSP(st,&ksp));
      73           2 :   PetscCall(KSPSetType(ksp,KSPBCGS));
      74           2 :   PetscCall(KSPGetPC(ksp,&pc));
      75           2 :   PetscCall(PCSetType(pc,PCJACOBI));
      76           2 :   PetscCall(EPSSetFromOptions(eps));
      77             : 
      78             :   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      79             :         Compute singular values
      80             :      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
      81             : 
      82           2 :   PetscCall(SVDCreate(PETSC_COMM_WORLD,&svd));
      83           2 :   PetscCall(SVDSetOperators(svd,A,NULL));
      84           2 :   PetscCall(SVDSetType(svd,SVDCROSS));
      85           2 :   PetscCall(SVDCrossSetEPS(svd,eps));
      86           2 :   PetscCall(SVDSetWhichSingularTriplets(svd,SVD_SMALLEST));
      87           2 :   PetscCall(SVDSetFromOptions(svd));
      88           2 :   PetscCall(PetscObjectTypeCompare((PetscObject)svd,SVDCROSS,&flg));
      89           2 :   if (flg) {
      90           2 :     PetscCall(SVDCrossGetExplicitMatrix(svd,&expmat));
      91           2 :     if (expmat) PetscCall(PetscPrintf(PETSC_COMM_WORLD," Using explicit matrix with cross solver\n"));
      92             :   }
      93           2 :   PetscCall(SVDSolve(svd));
      94             : 
      95             :   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      96             :                     Display solution and clean up
      97             :      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
      98           2 :   PetscCall(SVDErrorView(svd,SVD_ERROR_NORM,PETSC_VIEWER_STDOUT_WORLD));
      99           2 :   PetscCall(SVDDestroy(&svd));
     100           2 :   PetscCall(EPSDestroy(&eps));
     101           2 :   PetscCall(MatDestroy(&A));
     102           2 :   PetscCall(SlepcFinalize());
     103             :   return 0;
     104             : }
     105             : 
     106             : /*TEST
     107             : 
     108             :    testset:
     109             :       output_file: output/test6_1.out
     110             :       test:
     111             :          suffix: 1_subspace
     112             :          args: -eps_type subspace
     113             :       test:
     114             :          suffix: 1_lobpcg
     115             :          args: -eps_type lobpcg -st_type precond
     116             :       test:
     117             :          suffix: 2_cuda
     118             :          args: -eps_type subspace -mat_type aijcusparse
     119             :          requires: cuda
     120             :       test:
     121             :          suffix: 2_hip
     122             :          args: -eps_type subspace -mat_type aijhipsparse
     123             :          requires: hip
     124             : 
     125             : TEST*/