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;

 27:   PetscFunctionBeginUser;
 28:   PetscCall(SlepcInitialize(&argc,&argv,(char*)0,help));
 29:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
 30:   PetscCall(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:   PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
 37:   PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n));
 38:   PetscCall(MatSetFromOptions(A));

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

 51:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 52:      Compute the split preconditioner matrix (one diagonal)
 53:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 55:   PetscCall(MatCreate(PETSC_COMM_WORLD,&Pa));
 56:   PetscCall(MatSetSizes(Pa,PETSC_DECIDE,PETSC_DECIDE,n,n));
 57:   PetscCall(MatSetFromOptions(Pa));

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

 64:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 65:                 Create the spectral transformation object
 66:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

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

 77:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 78:                Form the preconditioner matrix and print it
 79:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

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

 90:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 91:                     Apply the operator
 92:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

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

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

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

123: /*TEST

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

130: TEST*/