Actual source code: test7.c

slepc-3.18.3 2023-03-24
Report Typos and Errors
  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 ST with one matrix and split preconditioner.\n\n";

 13: #include <slepcst.h>

 15: int main(int argc,char **argv)
 16: {
 17:   Mat            A,Pa,Pmat,mat[1];
 18:   ST             st;
 19:   KSP            ksp;
 20:   PC             pc;
 21:   Vec            v,w;
 22:   STType         type;
 23:   PetscBool      flg;
 24:   PetscScalar    sigma;
 25:   PetscInt       n=10,i,Istart,Iend;

 28:   SlepcInitialize(&argc,&argv,(char*)0,help);
 29:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
 30:   PetscPrintf(PETSC_COMM_WORLD,"\n1-D Laplacian, n=%" PetscInt_FMT "\n\n",n);

 32:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 33:      Compute the operator matrix for the 1-D Laplacian
 34:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 36:   MatCreate(PETSC_COMM_WORLD,&A);
 37:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);
 38:   MatSetFromOptions(A);
 39:   MatSetUp(A);

 41:   MatGetOwnershipRange(A,&Istart,&Iend);
 42:   for (i=Istart;i<Iend;i++) {
 43:     if (i>0) MatSetValue(A,i,i-1,-1.0,INSERT_VALUES);
 44:     if (i<n-1) MatSetValue(A,i,i+1,-1.0,INSERT_VALUES);
 45:     MatSetValue(A,i,i,2.0,INSERT_VALUES);
 46:   }
 47:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 48:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
 49:   MatCreateVecs(A,&v,&w);
 50:   VecSet(v,1.0);

 52:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 53:      Compute the split preconditioner matrix (one diagonal)
 54:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 56:   MatCreate(PETSC_COMM_WORLD,&Pa);
 57:   MatSetSizes(Pa,PETSC_DECIDE,PETSC_DECIDE,n,n);
 58:   MatSetFromOptions(Pa);
 59:   MatSetUp(Pa);

 61:   MatGetOwnershipRange(Pa,&Istart,&Iend);
 62:   for (i=Istart;i<Iend;i++) MatSetValue(Pa,i,i,2.0,INSERT_VALUES);
 63:   MatAssemblyBegin(Pa,MAT_FINAL_ASSEMBLY);
 64:   MatAssemblyEnd(Pa,MAT_FINAL_ASSEMBLY);

 66:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 67:                 Create the spectral transformation object
 68:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 70:   STCreate(PETSC_COMM_WORLD,&st);
 71:   mat[0] = A;
 72:   STSetMatrices(st,1,mat);
 73:   mat[0] = Pa;
 74:   STSetSplitPreconditioner(st,1,mat,SAME_NONZERO_PATTERN);
 75:   STSetTransform(st,PETSC_TRUE);
 76:   STSetFromOptions(st);
 77:   STCayleySetAntishift(st,-0.3);   /* only relevant for cayley */

 79:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 80:                Form the preconditioner matrix and print it
 81:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 83:   PetscObjectTypeCompareAny((PetscObject)st,&flg,STSINVERT,STCAYLEY,"");
 84:   if (flg) {
 85:     STGetKSP(st,&ksp);
 86:     KSPGetPC(ksp,&pc);
 87:     STGetOperator(st,NULL);
 88:     PCGetOperators(pc,NULL,&Pmat);
 89:     MatView(Pmat,NULL);
 90:   }

 92:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 93:                     Apply the operator
 94:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 96:   /* sigma=0.0 */
 97:   STSetUp(st);
 98:   STGetType(st,&type);
 99:   PetscPrintf(PETSC_COMM_WORLD,"ST type %s\n",type);
100:   STApply(st,v,w);
101:   VecView(w,NULL);

103:   /* sigma=0.1 */
104:   sigma = 0.1;
105:   STSetShift(st,sigma);
106:   STGetShift(st,&sigma);
107:   PetscPrintf(PETSC_COMM_WORLD,"With shift=%g\n",(double)PetscRealPart(sigma));
108:   if (flg) {
109:     STGetOperator(st,NULL);
110:     PCGetOperators(pc,NULL,&Pmat);
111:     MatView(Pmat,NULL);
112:   }
113:   STApply(st,v,w);
114:   VecView(w,NULL);

116:   STDestroy(&st);
117:   MatDestroy(&A);
118:   MatDestroy(&Pa);
119:   VecDestroy(&v);
120:   VecDestroy(&w);
121:   SlepcFinalize();
122:   return 0;
123: }

125: /*TEST

127:    test:
128:       suffix: 1
129:       args: -st_type {{cayley shift sinvert}separate output}
130:       requires: !single

132: TEST*/