Date: 2026-03-09T09:12:16+00:00

Actual source code: test3.c

      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.\n\n";

     13: #include <slepcst.h>

     15: int main(int argc,char **argv)
     16: {
     17:   Mat            A,B,M,mat[2];
     18:   ST             st;
     19:   Vec            v,w;
     20:   STType         type;
     21:   PetscScalar    sigma,tau;
     22:   PetscInt       n=10,i,Istart,Iend;

     24:   PetscFunctionBeginUser;
     25:   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
     26:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
     27:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\n1-D Laplacian plus diagonal, n=%" PetscInt_FMT "\n\n",n));

     29:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     30:      Compute the operator matrix for the 1-D Laplacian
     31:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     33:   PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
     34:   PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n));
     35:   PetscCall(MatSetFromOptions(A));

     37:   PetscCall(MatCreate(PETSC_COMM_WORLD,&B));
     38:   PetscCall(MatSetSizes(B,PETSC_DECIDE,PETSC_DECIDE,n,n));
     39:   PetscCall(MatSetFromOptions(B));

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

     57:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     58:                 Create the spectral transformation object
     59:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     61:   PetscCall(STCreate(PETSC_COMM_WORLD,&st));
     62:   mat[0] = A;
     63:   mat[1] = B;
     64:   PetscCall(STSetMatrices(st,2,mat));
     65:   PetscCall(STSetTransform(st,PETSC_TRUE));
     66:   PetscCall(STSetFromOptions(st));

     68:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     69:               Apply the transformed operator for several ST's
     70:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     72:   /* shift, sigma=0.0 */
     73:   PetscCall(STSetUp(st));
     74:   PetscCall(STGetType(st,&type));
     75:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"ST type %s\n",type));
     76:   PetscCall(STApply(st,v,w));
     77:   PetscCall(VecView(w,NULL));

     79:   /* shift, sigma=0.1 */
     80:   sigma = 0.1;
     81:   PetscCall(STSetShift(st,sigma));
     82:   PetscCall(STGetShift(st,&sigma));
     83:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"With shift=%g\n",(double)PetscRealPart(sigma)));
     84:   PetscCall(STApply(st,v,w));
     85:   PetscCall(VecView(w,NULL));

     87:   /* sinvert, sigma=0.1 */
     88:   PetscCall(STPostSolve(st));   /* undo changes if inplace */
     89:   PetscCall(STSetType(st,STSINVERT));
     90:   PetscCall(STGetType(st,&type));
     91:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"ST type %s\n",type));
     92:   PetscCall(STGetShift(st,&sigma));
     93:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"With shift=%g\n",(double)PetscRealPart(sigma)));
     94:   PetscCall(STApply(st,v,w));
     95:   PetscCall(VecView(w,NULL));

     97:   /* sinvert, sigma=-0.5 */
     98:   sigma = -0.5;
     99:   PetscCall(STSetShift(st,sigma));
    100:   PetscCall(STGetShift(st,&sigma));
    101:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"With shift=%g\n",(double)PetscRealPart(sigma)));
    102:   PetscCall(STApply(st,v,w));
    103:   PetscCall(VecView(w,NULL));

    105:   /* cayley, sigma=-0.5, tau=-0.5 (equal to sigma by default) */
    106:   PetscCall(STPostSolve(st));   /* undo changes if inplace */
    107:   PetscCall(STSetType(st,STCAYLEY));
    108:   PetscCall(STSetUp(st));
    109:   PetscCall(STGetType(st,&type));
    110:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"ST type %s\n",type));
    111:   PetscCall(STGetShift(st,&sigma));
    112:   PetscCall(STCayleyGetAntishift(st,&tau));
    113:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"With shift=%g, antishift=%g\n",(double)PetscRealPart(sigma),(double)PetscRealPart(tau)));
    114:   PetscCall(STApply(st,v,w));
    115:   PetscCall(VecView(w,NULL));

    117:   /* cayley, sigma=1.1, tau=1.1 (still equal to sigma) */
    118:   sigma = 1.1;
    119:   PetscCall(STSetShift(st,sigma));
    120:   PetscCall(STGetShift(st,&sigma));
    121:   PetscCall(STCayleyGetAntishift(st,&tau));
    122:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"With shift=%g, antishift=%g\n",(double)PetscRealPart(sigma),(double)PetscRealPart(tau)));
    123:   PetscCall(STApply(st,v,w));
    124:   PetscCall(VecView(w,NULL));

    126:   /* cayley, sigma=1.1, tau=-1.0 */
    127:   tau = -1.0;
    128:   PetscCall(STCayleySetAntishift(st,tau));
    129:   PetscCall(STGetShift(st,&sigma));
    130:   PetscCall(STCayleyGetAntishift(st,&tau));
    131:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"With shift=%g, antishift=%g\n",(double)PetscRealPart(sigma),(double)PetscRealPart(tau)));
    132:   PetscCall(STApply(st,v,w));
    133:   PetscCall(VecView(w,NULL));

    135:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    136:                   Check inner product matrix in Cayley
    137:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
    138:   PetscCall(STGetBilinearForm(st,&M));
    139:   PetscCall(MatMult(M,v,w));
    140:   PetscCall(VecView(w,NULL));

    142:   PetscCall(STDestroy(&st));
    143:   PetscCall(MatDestroy(&A));
    144:   PetscCall(MatDestroy(&B));
    145:   PetscCall(MatDestroy(&M));
    146:   PetscCall(VecDestroy(&v));
    147:   PetscCall(VecDestroy(&w));
    148:   PetscCall(SlepcFinalize());
    149:   return 0;
    150: }

    152: /*TEST

    154:    test:
    155:       suffix: 1
    156:       args: -st_matmode {{copy inplace shell}}
    157:       requires: !single

    159: TEST*/