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[] = "Computes exp(t*A)*v for a matrix loaded from file.\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:   PetscReal          norm;
 24:   PetscScalar        t=2.0;
 25:   Vec                v,y;
 26:   PetscViewer        viewer;
 27:   PetscBool          flg;
 28:   char               filename[PETSC_MAX_PATH_LEN];
 29:   MFNConvergedReason reason;

 31:   PetscFunctionBeginUser;
 32:   PetscCall(SlepcInitialize(&argc,&argv,(char*)0,help));

 34:   PetscCall(PetscOptionsGetScalar(NULL,NULL,"-t",&t,NULL));
 35:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nMatrix exponential y=exp(t*A)*e, loaded from file\n\n"));

 37:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 38:                 Load matrix A from binary file
 39:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

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

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

 55:   /* set v = ones(n,1) */
 56:   PetscCall(MatCreateVecs(A,&v,&y));
 57:   PetscCall(VecSet(v,1.0));

 59:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 60:                 Create the solver and set various options
 61:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 63:   PetscCall(MFNCreate(PETSC_COMM_WORLD,&mfn));
 64:   PetscCall(MFNSetOperator(mfn,A));
 65:   PetscCall(MFNGetFN(mfn,&f));
 66:   PetscCall(FNSetType(f,FNEXP));
 67:   PetscCall(FNSetScale(f,t,1.0));
 68:   PetscCall(MFNSetFromOptions(mfn));

 70:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 71:                       Solve the problem, y=exp(t*A)*v
 72:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

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

 80:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 81:                       Solve the problem, y=exp(t*A^T)*v
 82:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 84:   PetscCall(MFNSolveTranspose(mfn,v,y));
 85:   PetscCall(MFNGetConvergedReason(mfn,&reason));
 86:   PetscCheck(reason>=0,PETSC_COMM_WORLD,PETSC_ERR_CONV_FAILED,"Solver did not converge");
 87:   PetscCall(VecNorm(y,NORM_2,&norm));
 88:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," With transpose: computed vector has norm %g\n\n",(double)norm));

 90:   /*
 91:      Free work space
 92:   */
 93:   PetscCall(MFNDestroy(&mfn));
 94:   PetscCall(MatDestroy(&A));
 95:   PetscCall(VecDestroy(&v));
 96:   PetscCall(VecDestroy(&y));
 97:   PetscCall(SlepcFinalize());
 98:   return 0;
 99: }

101: /*TEST

103:    testset:
104:       args: -file ${DATAFILESPATH}/matrices/real/bfw782a.petsc -mfn_type {{krylov expokit}} -t 0.05
105:       requires: double !complex datafilespath !defined(PETSC_USE_64BIT_INDICES)
106:       output_file: output/test1_1.out
107:       test:
108:          suffix: 1
109:       test:
110:          suffix: 1_cuda
111:          args: -mat_type aijcusparse
112:          requires: cuda

114:    testset:
115:       args: -file ${DATAFILESPATH}/matrices/complex/qc324.petsc -mfn_type {{krylov expokit}}
116:       requires: double complex datafilespath !defined(PETSC_USE_64BIT_INDICES)
117:       output_file: output/test1_2.out
118:       test:
119:          suffix: 2
120:       test:
121:          suffix: 2_cuda
122:          args: -mat_type aijcusparse
123:          requires: cuda

125: TEST*/