Actual source code: test38.c

slepc-3.18.3 2023-03-24
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  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[] = "Test EPSLYAPII interface functions.\n\n"
 12:   "Based on ex2.\n"
 13:   "The command line options are:\n"
 14:   "  -n <n>, where <n> = number of grid subdivisions in x dimension.\n"
 15:   "  -m <m>, where <m> = number of grid subdivisions in y dimension.\n"
 16:   "  -shift <sigma>, where <sigma> = shift of origin.\n\n";

 18: #include <slepceps.h>

 20: int main(int argc,char **argv)
 21: {
 22:   Mat            A;
 23:   EPS            eps;
 24:   PetscInt       N,n=10,m,Istart,Iend,II,i,j,rkl,rkc;
 25:   PetscBool      flag,terse;
 26:   PetscReal      sigma=8.0;

 29:   SlepcInitialize(&argc,&argv,(char*)0,help);
 30:   PetscOptionsGetReal(NULL,NULL,"-shift",&sigma,NULL);
 31:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
 32:   PetscOptionsGetInt(NULL,NULL,"-m",&m,&flag);
 33:   if (!flag) m=n;
 34:   N = n*m;
 35:   PetscPrintf(PETSC_COMM_WORLD,"\nShifted 2-D Laplacian Eigenproblem, N=%" PetscInt_FMT " (%" PetscInt_FMT "x%" PetscInt_FMT " grid) sigma=%.1f\n\n",N,n,m,(double)sigma);

 37:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 38:                     Create the 2-D Laplacian
 39:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 41:   MatCreate(PETSC_COMM_WORLD,&A);
 42:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,N,N);
 43:   MatSetFromOptions(A);
 44:   MatSetUp(A);
 45:   MatGetOwnershipRange(A,&Istart,&Iend);
 46:   for (II=Istart;II<Iend;II++) {
 47:     i = II/n; j = II-i*n;
 48:     if (i>0) MatSetValue(A,II,II-n,-1.0,INSERT_VALUES);
 49:     if (i<m-1) MatSetValue(A,II,II+n,-1.0,INSERT_VALUES);
 50:     if (j>0) MatSetValue(A,II,II-1,-1.0,INSERT_VALUES);
 51:     if (j<n-1) MatSetValue(A,II,II+1,-1.0,INSERT_VALUES);
 52:     MatSetValue(A,II,II,4.0-sigma,INSERT_VALUES);
 53:   }
 54:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 55:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

 57:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 58:                 Create the eigensolver and set various options
 59:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 61:   EPSCreate(PETSC_COMM_WORLD,&eps);
 62:   EPSSetOperators(eps,A,NULL);
 63:   EPSSetProblemType(eps,EPS_HEP);
 64:   EPSSetWhichEigenpairs(eps,EPS_LARGEST_REAL);
 65:   EPSSetType(eps,EPSLYAPII);
 66:   EPSSetFromOptions(eps);

 68:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 69:                 Solve the problem and display the solution
 70:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 72:   EPSSolve(eps);

 74:   /* print solver information */
 75:   PetscObjectTypeCompare((PetscObject)eps,EPSLYAPII,&flag);
 76:   if (flag) {
 77:     EPSLyapIIGetRanks(eps,&rkc,&rkl);
 78:     PetscPrintf(PETSC_COMM_WORLD," EPSLYAPII ranks: for Lyapunov solver=%" PetscInt_FMT ", after compression=%" PetscInt_FMT "\n\n",rkl,rkc);
 79:   }

 81:   PetscOptionsHasName(NULL,NULL,"-terse",&terse);
 82:   if (terse) EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
 83:   else {
 84:     PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
 85:     EPSConvergedReasonView(eps,PETSC_VIEWER_STDOUT_WORLD);
 86:     EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
 87:     PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
 88:   }

 90:   EPSDestroy(&eps);
 91:   MatDestroy(&A);
 92:   SlepcFinalize();
 93:   return 0;
 94: }

 96: /*TEST

 98:    test:
 99:       args: -eps_view -terse
100:       filter: grep -v tolerance | sed -e "s/symmetric/hermitian/"

102: TEST*/