1: /*
  2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  4:    Copyright (c) 2002-, 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 problem with user-defined stopping test.\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>
 17: #include <petsctime.h>

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

 22:               |  1  2                     |
 23:               |     1  2                  |
 24:               |        1  2               |
 25:           A = |          .  .             |
 26:               |             .  .          |
 27:               |                1  2       |
 28:               |                   1  2    |
 29:  */

 31: /*
 32:     Function for user-defined stopping test.

 34:     Checks that the computing time has not exceeded the deadline.
 35: */
 36: PetscErrorCode MyStoppingTest(SVD svd,PetscInt its,PetscInt max_it,PetscInt nconv,PetscInt nev,SVDConvergedReason *reason,void *ctx)
 37: {
 38:   PetscLogDouble now,deadline = *(PetscLogDouble*)ctx;

 40:   PetscFunctionBeginUser;
 41:   /* check if usual termination conditions are met */
 42:   PetscCall(SVDStoppingBasic(svd,its,max_it,nconv,nev,reason,NULL));
 43:   if (*reason==SVD_CONVERGED_ITERATING) {
 44:     /* check if deadline has expired */
 45:     PetscCall(PetscTime(&now));
 46:     if (now>deadline) *reason = SVD_CONVERGED_USER;
 47:   }
 48:   PetscFunctionReturn(PETSC_SUCCESS);
 49: }

 51: int main(int argc,char **argv)
 52: {
 53:   Mat                A;
 54:   SVD                svd;
 55:   SVDConvergedReason reason;
 56:   PetscInt           m=20,n,Istart,Iend,i,col[2],nconv;
 57:   PetscReal          seconds=2.5;     /* maximum time allowed for computation */
 58:   PetscLogDouble     deadline;        /* time to abort computation */
 59:   PetscScalar        value[] = { 1, 2 };
 60:   PetscBool          terse,flg;
 61:   PetscViewer        viewer;

 63:   PetscFunctionBeginUser;
 64:   PetscCall(SlepcInitialize(&argc,&argv,(char*)0,help));

 66:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL));
 67:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,&flg));
 68:   if (!flg) n=m+2;
 69:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nRectangular bidiagonal matrix, m=%" PetscInt_FMT " n=%" PetscInt_FMT "\n\n",m,n));
 70:   PetscCall(PetscOptionsGetReal(NULL,NULL,"-seconds",&seconds,NULL));
 71:   deadline = seconds;
 72:   PetscCall(PetscTimeAdd(&deadline));

 74:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 75:         Generate the matrix
 76:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 78:   PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
 79:   PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,m,n));
 80:   PetscCall(MatSetFromOptions(A));
 81:   PetscCall(MatGetOwnershipRange(A,&Istart,&Iend));
 82:   for (i=Istart;i<Iend;i++) {
 83:     col[0]=i; col[1]=i+1;
 84:     if (i<n-1) PetscCall(MatSetValues(A,1,&i,2,col,value,INSERT_VALUES));
 85:     else if (i==n-1) PetscCall(MatSetValue(A,i,col[0],value[0],INSERT_VALUES));
 86:   }
 87:   PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY));
 88:   PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY));

 90:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 91:         Compute singular values
 92:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 94:   PetscCall(SVDCreate(PETSC_COMM_WORLD,&svd));
 95:   PetscCall(SVDSetOperators(svd,A,NULL));
 96:   PetscCall(SVDSetWhichSingularTriplets(svd,SVD_SMALLEST));
 97:   PetscCall(SVDSetTolerances(svd,PETSC_DEFAULT,1000));
 98:   PetscCall(SVDSetType(svd,SVDTRLANCZOS));
 99:   PetscCall(SVDSetStoppingTestFunction(svd,MyStoppingTest,&deadline,NULL));
100:   PetscCall(SVDSetFromOptions(svd));

102:   /* call the solver */
103:   PetscCall(SVDSolve(svd));

105:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
106:                     Display solution and clean up
107:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

109:   /* show detailed info unless -terse option is given by user */
110:   PetscCall(PetscOptionsHasName(NULL,NULL,"-terse",&terse));
111:   if (terse) PetscCall(SVDErrorView(svd,SVD_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD));
112:   else {
113:     PetscCall(PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer));
114:     PetscCall(PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL));
115:     PetscCall(SVDGetConvergedReason(svd,&reason));
116:     if (reason!=SVD_CONVERGED_USER) {
117:       PetscCall(SVDConvergedReasonView(svd,viewer));
118:       PetscCall(SVDErrorView(svd,SVD_ERROR_RELATIVE,viewer));
119:     } else {
120:       PetscCall(SVDGetConverged(svd,&nconv));
121:       PetscCall(PetscViewerASCIIPrintf(viewer,"SVD solve finished with %" PetscInt_FMT " converged eigenpairs; reason=%s\n",nconv,SVDConvergedReasons[reason]));
122:     }
123:     PetscCall(PetscViewerPopFormat(viewer));
124:   }
125:   PetscCall(SVDDestroy(&svd));
126:   PetscCall(MatDestroy(&A));
127:   PetscCall(SlepcFinalize());
128:   return 0;
129: }

131: /*TEST

133:    test:
134:       suffix: 1
135:       args: -m 750 -seconds 0.1 -svd_max_it 10000
136:       requires: !single

138: TEST*/