Actual source code: test8.c

slepc-3.17.1 2022-04-11
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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 ST with two matrices and split preconditioner.\n\n";

 13: #include <slepcst.h>

 15: int main(int argc,char **argv)
 16: {
 17:   Mat            A,B,Pa,Pb,Pmat,mat[2];
 18:   ST             st;
 19:   KSP            ksp;
 20:   PC             pc;
 21:   Vec            v,w;
 22:   STType         type;
 23:   PetscScalar    sigma;
 24:   PetscInt       n=10,i,Istart,Iend;

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

 30:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 31:      Compute the operator matrices (1-D Laplacian and diagonal)
 32:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

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

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

 44:   MatGetOwnershipRange(A,&Istart,&Iend);
 45:   for (i=Istart;i<Iend;i++) {
 46:     MatSetValue(A,i,i,2.0,INSERT_VALUES);
 47:     if (i>0) {
 48:       MatSetValue(A,i,i-1,-1.0,INSERT_VALUES);
 49:       MatSetValue(B,i,i,(PetscScalar)i,INSERT_VALUES);
 50:     } else MatSetValue(B,i,i,-1.0,INSERT_VALUES);
 51:     if (i<n-1) MatSetValue(A,i,i+1,-1.0,INSERT_VALUES);
 52:   }
 53:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 54:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
 55:   MatAssemblyBegin(B,MAT_FINAL_ASSEMBLY);
 56:   MatAssemblyEnd(B,MAT_FINAL_ASSEMBLY);
 57:   MatCreateVecs(A,&v,&w);
 58:   VecSet(v,1.0);

 60:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 61:      Compute the split preconditioner matrices (two diagonals)
 62:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 64:   MatCreate(PETSC_COMM_WORLD,&Pa);
 65:   MatSetSizes(Pa,PETSC_DECIDE,PETSC_DECIDE,n,n);
 66:   MatSetFromOptions(Pa);
 67:   MatSetUp(Pa);

 69:   MatCreate(PETSC_COMM_WORLD,&Pb);
 70:   MatSetSizes(Pb,PETSC_DECIDE,PETSC_DECIDE,n,n);
 71:   MatSetFromOptions(Pb);
 72:   MatSetUp(Pb);

 74:   MatGetOwnershipRange(Pa,&Istart,&Iend);
 75:   for (i=Istart;i<Iend;i++) {
 76:     MatSetValue(Pa,i,i,2.0,INSERT_VALUES);
 77:     if (i>0) MatSetValue(Pb,i,i,(PetscScalar)i,INSERT_VALUES);
 78:     else MatSetValue(Pb,i,i,-1.0,INSERT_VALUES);
 79:   }
 80:   MatAssemblyBegin(Pa,MAT_FINAL_ASSEMBLY);
 81:   MatAssemblyEnd(Pa,MAT_FINAL_ASSEMBLY);
 82:   MatAssemblyBegin(Pb,MAT_FINAL_ASSEMBLY);
 83:   MatAssemblyEnd(Pb,MAT_FINAL_ASSEMBLY);

 85:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 86:                 Create the spectral transformation object
 87:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 89:   STCreate(PETSC_COMM_WORLD,&st);
 90:   mat[0] = A;
 91:   mat[1] = B;
 92:   STSetMatrices(st,2,mat);
 93:   mat[0] = Pa;
 94:   mat[1] = Pb;
 95:   STSetSplitPreconditioner(st,2,mat,SAME_NONZERO_PATTERN);
 96:   STSetTransform(st,PETSC_TRUE);
 97:   STSetFromOptions(st);
 98:   STCayleySetAntishift(st,-0.2);   /* only relevant for cayley */

100:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
101:                Form the preconditioner matrix and print it
102:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

104:   STGetKSP(st,&ksp);
105:   KSPGetPC(ksp,&pc);
106:   STGetOperator(st,NULL);
107:   PCGetOperators(pc,NULL,&Pmat);
108:   MatView(Pmat,NULL);

110:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
111:                    Apply the operator
112:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

114:   /* sigma=0.0 */
115:   STSetUp(st);
116:   STGetType(st,&type);
117:   PetscPrintf(PETSC_COMM_WORLD,"ST type %s\n",type);
118:   STApply(st,v,w);
119:   VecView(w,NULL);

121:   /* sigma=0.1 */
122:   sigma = 0.1;
123:   STSetShift(st,sigma);
124:   STGetShift(st,&sigma);
125:   PetscPrintf(PETSC_COMM_WORLD,"With shift=%g\n",(double)PetscRealPart(sigma));
126:   STGetOperator(st,NULL);
127:   PCGetOperators(pc,NULL,&Pmat);
128:   MatView(Pmat,NULL);
129:   STApply(st,v,w);
130:   VecView(w,NULL);

132:   STDestroy(&st);
133:   MatDestroy(&A);
134:   MatDestroy(&B);
135:   MatDestroy(&Pa);
136:   MatDestroy(&Pb);
137:   VecDestroy(&v);
138:   VecDestroy(&w);
139:   SlepcFinalize();
140:   return 0;
141: }

143: /*TEST

145:    test:
146:       suffix: 1
147:       args: -st_type {{cayley shift sinvert}separate output}
148:       requires: !single

150: TEST*/