Date: 2022-03-31T15:29:02+00:00

Actual source code: test8.c
slepc-3.17.0 2022-03-31
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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*/