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[] = "Tests multiple calls to EPSSolve with matrices of different local size.\n\n"
 12:   "The command line options are:\n"
 13:   "  -n <n>, where <n> = number of grid subdivisions in x dimension.\n"
 14:   "  -m <m>, where <m> = number of grid subdivisions in y dimension.\n\n";

 16: #include <slepceps.h>

 18: /*
 19:    Create 2-D Laplacian matrix
 20: */
 21: PetscErrorCode Laplacian(MPI_Comm comm,PetscInt n,PetscInt m,PetscInt shift,Mat *A)
 22: {
 23:   PetscInt       N = n*m,i,j,II,Istart,Iend,nloc;
 24:   PetscMPIInt    rank;

 26:   PetscFunctionBeginUser;
 27:   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD,&rank));
 28:   nloc = PETSC_DECIDE;
 29:   PetscCall(PetscSplitOwnership(comm,&nloc,&N));
 30:   if (rank==0) nloc += shift;
 31:   else if (rank==1) nloc -= shift;

 33:   PetscCall(MatCreate(comm,A));
 34:   PetscCall(MatSetSizes(*A,nloc,nloc,N,N));
 35:   PetscCall(MatSetFromOptions(*A));
 36:   PetscCall(MatGetOwnershipRange(*A,&Istart,&Iend));
 37:   for (II=Istart;II<Iend;II++) {
 38:     i = II/n; j = II-i*n;
 39:     if (i>0) PetscCall(MatSetValue(*A,II,II-n,-1.0,INSERT_VALUES));
 40:     if (i<m-1) PetscCall(MatSetValue(*A,II,II+n,-1.0,INSERT_VALUES));
 41:     if (j>0) PetscCall(MatSetValue(*A,II,II-1,-1.0,INSERT_VALUES));
 42:     if (j<n-1) PetscCall(MatSetValue(*A,II,II+1,-1.0,INSERT_VALUES));
 43:     PetscCall(MatSetValue(*A,II,II,4.0,INSERT_VALUES));
 44:   }
 45:   PetscCall(MatAssemblyBegin(*A,MAT_FINAL_ASSEMBLY));
 46:   PetscCall(MatAssemblyEnd(*A,MAT_FINAL_ASSEMBLY));
 47:   PetscFunctionReturn(PETSC_SUCCESS);
 48: }

 50: int main(int argc,char **argv)
 51: {
 52:   Mat            A,B;
 53:   EPS            eps;
 54:   PetscInt       N,n=10,m=11,nev=3;
 55:   PetscMPIInt    size;
 56:   PetscBool      flag,terse;

 58:   PetscFunctionBeginUser;
 59:   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
 60:   PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD,&size));
 61:   PetscCheck(size>1,PETSC_COMM_WORLD,PETSC_ERR_WRONG_MPI_SIZE,"This example requires at least two processes");
 62:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
 63:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-m",&m,&flag));
 64:   N = n*m;
 65:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\n2-D Laplacian Eigenproblem, N=%" PetscInt_FMT " (%" PetscInt_FMT "x%" PetscInt_FMT " grid)\n\n",N,n,m));

 67:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 68:                 Create 2-D Laplacian matrices
 69:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 71:   PetscCall(Laplacian(PETSC_COMM_WORLD,n,m,1,&A));
 72:   PetscCall(Laplacian(PETSC_COMM_WORLD,n,m,-1,&B));

 74:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 75:         Create the eigensolver, set options and solve the eigensystem
 76:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 78:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"First solve:\n\n"));
 79:   PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));
 80:   PetscCall(EPSSetOperators(eps,A,NULL));
 81:   PetscCall(EPSSetProblemType(eps,EPS_HEP));
 82:   PetscCall(EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL));
 83:   PetscCall(EPSSetDimensions(eps,nev,PETSC_DETERMINE,PETSC_DETERMINE));
 84:   PetscCall(EPSSetFromOptions(eps));

 86:   PetscCall(EPSSolve(eps));

 88:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 89:                     Display solution of first solve
 90:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 92:   PetscCall(PetscOptionsHasName(NULL,NULL,"-terse",&terse));
 93:   if (terse) PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL));
 94:   else {
 95:     PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL));
 96:     PetscCall(EPSConvergedReasonView(eps,PETSC_VIEWER_STDOUT_WORLD));
 97:     PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD));
 98:     PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
 99:   }

101:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
102:                        Solve with second matrix
103:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

105:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nSecond solve:\n\n"));
106:   /* PetscCall(EPSReset(eps)); */  /* not required, will be called in EPSSetOperators() */
107:   PetscCall(EPSSetOperators(eps,B,NULL));
108:   PetscCall(EPSSolve(eps));

110:   if (terse) PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL));
111:   else {
112:     PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL));
113:     PetscCall(EPSConvergedReasonView(eps,PETSC_VIEWER_STDOUT_WORLD));
114:     PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD));
115:     PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
116:   }

118:   PetscCall(EPSDestroy(&eps));
119:   PetscCall(MatDestroy(&A));
120:   PetscCall(MatDestroy(&B));
121:   PetscCall(SlepcFinalize());
122:   return 0;
123: }

125: /*TEST

127:    testset:
128:       nsize: 2
129:       requires: !single
130:       output_file: output/test39_1.out
131:       test:
132:          suffix: 1
133:          args: -eps_type {{krylovschur arnoldi lobpcg lapack}} -terse
134:       test:
135:          suffix: 1_lanczos
136:          args: -eps_type lanczos -eps_lanczos_reorthog local -terse

138: TEST*/