Actual source code: test3.c

slepc-3.11.2 2019-07-30
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  1: /*
  2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  4:    Copyright (c) 2002-2019, 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 MFN interface functions.\n\n"
 12:   "The command line options are:\n"
 13:   "  -n <n>, where <n> = number of grid subdivisions in x dimension.\n\n";

 15: #include <slepcmfn.h>

 17: int main(int argc,char **argv)
 18: {
 19:   Mat                  A,B;
 20:   MFN                  mfn;
 21:   FN                   f;
 22:   MFNConvergedReason   reason;
 23:   PetscReal            norm,tol;
 24:   Vec                  v,y;
 25:   PetscInt             N,n=4,Istart,Iend,i,j,II,ncv,its,maxit;
 26:   PetscBool            flg;
 27:   PetscErrorCode       ierr;
 28:   PetscViewerAndFormat *vf;

 30:   SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
 31:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
 32:   N = n*n;
 33:   PetscPrintf(PETSC_COMM_WORLD,"\nSquare root of Laplacian y=sqrt(A)*e_1, N=%D (%Dx%D grid)\n\n",N,n,n);

 35:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 36:                  Compute the discrete 2-D Laplacian, A
 37:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 39:   MatCreate(PETSC_COMM_WORLD,&A);
 40:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,N,N);
 41:   MatSetFromOptions(A);
 42:   MatSetUp(A);

 44:   MatGetOwnershipRange(A,&Istart,&Iend);
 45:   for (II=Istart;II<Iend;II++) {
 46:     i = II/n; j = II-i*n;
 47:     if (i>0) { MatSetValue(A,II,II-n,-1.0,INSERT_VALUES); }
 48:     if (i<n-1) { MatSetValue(A,II,II+n,-1.0,INSERT_VALUES); }
 49:     if (j>0) { MatSetValue(A,II,II-1,-1.0,INSERT_VALUES); }
 50:     if (j<n-1) { MatSetValue(A,II,II+1,-1.0,INSERT_VALUES); }
 51:     MatSetValue(A,II,II,4.0,INSERT_VALUES);
 52:   }

 54:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 55:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
 56:   MatSetOption(A,MAT_HERMITIAN,PETSC_TRUE);

 58:   MatCreateVecs(A,NULL,&v);
 59:   VecSetValue(v,0,1.0,INSERT_VALUES);
 60:   VecAssemblyBegin(v);
 61:   VecAssemblyEnd(v);
 62:   VecDuplicate(v,&y);

 64:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 65:              Create the solver, set the matrix and the function
 66:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 67:   MFNCreate(PETSC_COMM_WORLD,&mfn);
 68:   MFNSetOperator(mfn,A);
 69:   MFNGetFN(mfn,&f);
 70:   FNSetType(f,FNSQRT);

 72:   /* test some interface functions */
 73:   MFNGetOperator(mfn,&B);
 74:   MatView(B,PETSC_VIEWER_STDOUT_WORLD);
 75:   MFNSetOptionsPrefix(mfn,"myprefix_");
 76:   MFNSetTolerances(mfn,1e-4,500);
 77:   MFNSetDimensions(mfn,6);
 78:   MFNSetErrorIfNotConverged(mfn,PETSC_TRUE);
 79:   /* test monitors */
 80:   PetscViewerAndFormatCreate(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_DEFAULT,&vf);
 81:   MFNMonitorSet(mfn,(PetscErrorCode (*)(MFN,PetscInt,PetscReal,void*))MFNMonitorDefault,vf,(PetscErrorCode (*)(void**))PetscViewerAndFormatDestroy);
 82:   /* SVDMonitorCancel(svd); */
 83:   MFNSetFromOptions(mfn);

 85:   /* query properties and print them */
 86:   MFNGetTolerances(mfn,&tol,&maxit);
 87:   PetscPrintf(PETSC_COMM_WORLD," Tolerance: %g, max iterations: %D\n",(double)tol,maxit);
 88:   MFNGetDimensions(mfn,&ncv);
 89:   PetscPrintf(PETSC_COMM_WORLD," Subspace dimension: %D\n",ncv);
 90:   MFNGetErrorIfNotConverged(mfn,&flg);
 91:   if (flg) { PetscPrintf(PETSC_COMM_WORLD," Erroring out if convergence fails\n"); }

 93:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 94:                            Solve  y=sqrt(A)*v
 95:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 97:   MFNSolve(mfn,v,y);
 98:   MFNGetConvergedReason(mfn,&reason);
 99:   MFNGetIterationNumber(mfn,&its);
100:   PetscPrintf(PETSC_COMM_WORLD," Finished - converged reason = %d\n",(int)reason);
101:   /* PetscPrintf(PETSC_COMM_WORLD," its = %D\n",its); */
102:   VecNorm(y,NORM_2,&norm);
103:   PetscPrintf(PETSC_COMM_WORLD," sqrt(A)*v has norm %g\n",(double)norm);

105:   /*
106:      Free work space
107:   */
108:   MFNDestroy(&mfn);
109:   MatDestroy(&A);
110:   VecDestroy(&v);
111:   VecDestroy(&y);
112:   SlepcFinalize();
113:   return ierr;
114: }

116: /*TEST

118:    test:
119:       suffix: 1
120:       args: -myprefix_mfn_monitor_cancel -myprefix_mfn_converged_reason -myprefix_mfn_view

122: TEST*/