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[] = "Illustrates use of MFNSetBV().\n\n"
 12:   "The command line options are:\n"
 13:   "  -t <sval>, where <sval> = scalar value that multiplies the argument.\n"
 14:   "  -file <filename>, where <filename> = matrix file in PETSc binary form.\n\n";

 16: #include <slepcmfn.h>

 18: int main(int argc,char **argv)
 19: {
 20:   Mat                A;           /* problem matrix */
 21:   MFN                mfn;
 22:   FN                 f;
 23:   BV                 V;
 24:   PetscInt           k=8;
 25:   PetscReal          norm;
 26:   PetscScalar        t=2.0;
 27:   Vec                v,y;
 28:   PetscViewer        viewer;
 29:   PetscBool          flg;
 30:   char               filename[PETSC_MAX_PATH_LEN];
 31:   MFNConvergedReason reason;

 33:   PetscFunctionBeginUser;
 34:   PetscCall(SlepcInitialize(&argc,&argv,(char*)0,help));

 36:   PetscCall(PetscOptionsGetScalar(NULL,NULL,"-t",&t,NULL));
 37:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-k",&k,NULL));
 38:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nMatrix exponential y=exp(t*A)*e, loaded from file\n\n"));

 40:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 41:                 Load matrix A from binary file
 42:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 44:   PetscCall(PetscOptionsGetString(NULL,NULL,"-file",filename,sizeof(filename),&flg));
 45:   PetscCheck(flg,PETSC_COMM_WORLD,PETSC_ERR_USER_INPUT,"Must indicate a file name with the -file option");

 47: #if defined(PETSC_USE_COMPLEX)
 48:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Reading COMPLEX matrix from a binary file...\n"));
 49: #else
 50:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Reading REAL matrix from a binary file...\n"));
 51: #endif
 52:   PetscCall(PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_READ,&viewer));
 53:   PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
 54:   PetscCall(MatSetFromOptions(A));
 55:   PetscCall(MatLoad(A,viewer));
 56:   PetscCall(PetscViewerDestroy(&viewer));

 58:   /* set v = ones(n,1) */
 59:   PetscCall(MatCreateVecs(A,&v,&y));
 60:   PetscCall(VecSet(v,1.0));

 62:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 63:                         Create the BV object
 64:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 66:   PetscCall(BVCreate(PETSC_COMM_WORLD,&V));
 67:   PetscCall(PetscObjectSetName((PetscObject)V,"V"));
 68:   PetscCall(BVSetSizesFromVec(V,v,k));
 69:   PetscCall(BVSetFromOptions(V));

 71:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 72:                 Create the solver and set various options
 73:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 75:   PetscCall(MFNCreate(PETSC_COMM_WORLD,&mfn));
 76:   PetscCall(MFNSetOperator(mfn,A));
 77:   PetscCall(MFNSetBV(mfn,V));
 78:   PetscCall(MFNGetFN(mfn,&f));
 79:   PetscCall(FNSetType(f,FNEXP));
 80:   PetscCall(FNSetScale(f,t,1.0));
 81:   PetscCall(MFNSetDimensions(mfn,k));
 82:   PetscCall(MFNSetFromOptions(mfn));

 84:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 85:                       Solve the problem, y=exp(t*A)*v
 86:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 88:   PetscCall(MFNSolve(mfn,v,y));
 89:   PetscCall(MFNGetConvergedReason(mfn,&reason));
 90:   PetscCheck(reason>=0,PETSC_COMM_WORLD,PETSC_ERR_CONV_FAILED,"Solver did not converge");
 91:   PetscCall(VecNorm(y,NORM_2,&norm));
 92:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Computed vector at time t=%.4g has norm %g\n\n",(double)PetscRealPart(t),(double)norm));

 94:   /*
 95:      Free work space
 96:   */
 97:   PetscCall(BVDestroy(&V));
 98:   PetscCall(MFNDestroy(&mfn));
 99:   PetscCall(MatDestroy(&A));
100:   PetscCall(VecDestroy(&v));
101:   PetscCall(VecDestroy(&y));
102:   PetscCall(SlepcFinalize());
103:   return 0;
104: }

106: /*TEST

108:    test:
109:       suffix: 1
110:       args: -file ${SLEPC_DIR}/share/slepc/datafiles/matrices/bfw62b.petsc -k 12
111:       requires: double !complex !defined(PETSC_USE_64BIT_INDICES)

113:    test:
114:       suffix: 2
115:       args: -file ${DATAFILESPATH}/matrices/complex/qc324.petsc -k 12
116:       requires: double complex datafilespath !defined(PETSC_USE_64BIT_INDICES)

118: TEST*/