Actual source code: test6.c

slepc-3.11.2 2019-07-30
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  1: /*
  2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  4:    Copyright (c) 2002-2019, Universitat Politecnica de Valencia, Spain

  6:    This file is part of SLEPc.
  7:    SLEPc is distributed under a 2-clause BSD license (see LICENSE).
  8:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  9: */

 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";

 16: #include <slepcsvd.h>

 18: /*
 19:    This example computes the singular values of a rectangular bidiagonal matrix

 21:               |  1  2                     |
 22:               |     1  2                  |
 23:               |        1  2               |
 24:           A = |          .  .             |
 25:               |             .  .          |
 26:               |                1  2       |
 27:               |                   1  2    |
 28:  */

 30: int main(int argc,char **argv)
 31: {
 32:   Mat            A;
 33:   SVD            svd;
 34:   EPS            eps;
 35:   ST             st;
 36:   KSP            ksp;
 37:   PC             pc;
 38:   PetscInt       m=20,n,Istart,Iend,i,col[2];
 39:   PetscScalar    value[] = { 1, 2 };
 40:   PetscBool      flg;

 43:   SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
 44:   PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL);
 45:   PetscOptionsGetInt(NULL,NULL,"-n",&n,&flg);
 46:   if (!flg) n=m+2;
 47:   PetscPrintf(PETSC_COMM_WORLD,"\nRectangular bidiagonal matrix, m=%D n=%D\n\n",m,n);

 49:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 50:         Generate the matrix
 51:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 53:   MatCreate(PETSC_COMM_WORLD,&A);
 54:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,m,n);
 55:   MatSetFromOptions(A);
 56:   MatSetUp(A);
 57:   MatGetOwnershipRange(A,&Istart,&Iend);
 58:   for (i=Istart;i<Iend;i++) {
 59:     col[0]=i; col[1]=i+1;
 60:     if (i<n-1) {
 61:       MatSetValues(A,1,&i,2,col,value,INSERT_VALUES);
 62:     } else if (i==n-1) {
 63:       MatSetValue(A,i,col[0],value[0],INSERT_VALUES);
 64:     }
 65:   }
 66:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 67:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

 69:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 70:         Create a standalone EPS with appropriate settings
 71:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 73:   EPSCreate(PETSC_COMM_WORLD,&eps);
 74:   EPSGetST(eps,&st);
 75:   STSetType(st,STSINVERT);
 76:   STGetKSP(st,&ksp);
 77:   KSPSetType(ksp,KSPBCGS);
 78:   KSPGetPC(ksp,&pc);
 79:   PCSetType(pc,PCJACOBI);
 80:   EPSSetFromOptions(eps);

 82:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 83:         Compute singular values
 84:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 86:   SVDCreate(PETSC_COMM_WORLD,&svd);
 87:   SVDSetOperator(svd,A);
 88:   SVDSetType(svd,SVDCROSS);
 89:   SVDCrossSetEPS(svd,eps);
 90:   SVDSetWhichSingularTriplets(svd,SVD_SMALLEST);
 91:   SVDSetFromOptions(svd);
 92:   SVDSolve(svd);

 94:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 95:                     Display solution and clean up
 96:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 97:   SVDErrorView(svd,SVD_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
 98:   SVDDestroy(&svd);
 99:   EPSDestroy(&eps);
100:   MatDestroy(&A);
101:   SlepcFinalize();
102:   return ierr;
103: }

105: /*TEST

107:    testset:
108:       output_file: output/test6_1.out
109:       test:
110:          suffix: 1_subspace
111:          args: -eps_type subspace
112:       test:
113:          suffix: 1_lobpcg
114:          args: -eps_type lobpcg -st_type precond
115:       test:
116:          suffix: 2_cuda
117:          args: -eps_type subspace -mat_type aijcusparse
118:          requires: cuda

120: TEST*/