Date: 2021-09-20T09:43:56+00:00

Actual source code: test33.c
slepc-3.15.2 2021-09-20
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2021, 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 interface to external package BLZPACK.\n\n"
     12:   "This is based on ex12.c. The command line options are:\n"
     13:   "  -n <n>, where <n> = number of grid subdivisions in x dimension.\n"
     14:   "  -m <m>, where <m> = number of grid subdivisions in y dimension.\n\n";

     16: #include <slepceps.h>

     18: int main(int argc,char **argv)
     19: {
     20:   Mat            A,B;         /* matrices */
     21:   EPS            eps;         /* eigenproblem solver context */
     22:   ST             st;          /* spectral transformation context */
     23:   KSP            ksp;
     24:   PC             pc;
     25:   PetscInt       N,n=35,m,Istart,Iend,II,nev,i,j,bs,nsteps;
     26:   PetscBool      flag;
     27:   PetscReal      int0,int1;

     30:   SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;

     32:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
     33:   PetscOptionsGetInt(NULL,NULL,"-m",&m,&flag);
     34:   if (!flag) m=n;
     35:   N = n*m;
     36:   PetscPrintf(PETSC_COMM_WORLD,"\nSpectrum-slicing test, N=%D (%Dx%D grid)\n\n",N,n,m);

     38:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     39:      Compute the matrices that define the eigensystem, Ax=kBx
     40:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     42:   MatCreate(PETSC_COMM_WORLD,&A);
     43:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,N,N);
     44:   MatSetFromOptions(A);
     45:   MatSetUp(A);

     47:   MatCreate(PETSC_COMM_WORLD,&B);
     48:   MatSetSizes(B,PETSC_DECIDE,PETSC_DECIDE,N,N);
     49:   MatSetFromOptions(B);
     50:   MatSetUp(B);

     52:   MatGetOwnershipRange(A,&Istart,&Iend);
     53:   for (II=Istart;II<Iend;II++) {
     54:     i = II/n; j = II-i*n;
     55:     if (i>0) { MatSetValue(A,II,II-n,-1.0,INSERT_VALUES); }
     56:     if (i<m-1) { MatSetValue(A,II,II+n,-1.0,INSERT_VALUES); }
     57:     if (j>0) { MatSetValue(A,II,II-1,-1.0,INSERT_VALUES); }
     58:     if (j<n-1) { MatSetValue(A,II,II+1,-1.0,INSERT_VALUES); }
     59:     MatSetValue(A,II,II,4.0,INSERT_VALUES);
     60:     MatSetValue(B,II,II,2.0,INSERT_VALUES);
     61:   }
     62:   if (Istart==0) {
     63:     MatSetValue(B,0,0,6.0,INSERT_VALUES);
     64:     MatSetValue(B,0,1,-1.0,INSERT_VALUES);
     65:     MatSetValue(B,1,0,-1.0,INSERT_VALUES);
     66:     MatSetValue(B,1,1,1.0,INSERT_VALUES);
     67:   }

     69:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
     70:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
     71:   MatAssemblyBegin(B,MAT_FINAL_ASSEMBLY);
     72:   MatAssemblyEnd(B,MAT_FINAL_ASSEMBLY);

     74:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     75:                 Create the eigensolver and set various options
     76:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     78:   EPSCreate(PETSC_COMM_WORLD,&eps);
     79:   EPSSetOperators(eps,A,B);
     80:   EPSSetProblemType(eps,EPS_GHEP);
     81:   EPSSetType(eps,EPSBLZPACK);

     83:   /*
     84:      Set interval and other settings for spectrum slicing
     85:   */
     86:   EPSSetWhichEigenpairs(eps,EPS_ALL);
     87:   int0 = 1.1; int1 = 1.2;
     88:   EPSSetInterval(eps,int0,int1);
     89:   EPSSetDimensions(eps,100,PETSC_DEFAULT,PETSC_DEFAULT);
     90:   EPSGetST(eps,&st);
     91:   STSetType(st,STSINVERT);
     92:   STGetKSP(st,&ksp);
     93:   KSPGetPC(ksp,&pc);
     94:   KSPSetType(ksp,KSPPREONLY);
     95:   PCSetType(pc,PCCHOLESKY);

     97:   EPSBlzpackSetBlockSize(eps,4);
     98:   EPSBlzpackSetNSteps(eps,20);
     99:   EPSSetFromOptions(eps);

    101:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    102:            Compute all eigenvalues in interval and display info
    103:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    105:   EPSSolve(eps);
    106:   EPSBlzpackGetBlockSize(eps,&bs);
    107:   EPSBlzpackGetNSteps(eps,&nsteps);
    108:   PetscPrintf(PETSC_COMM_WORLD," Using block size %D, maximum number of steps %D\n",bs,nsteps);
    109:   EPSGetDimensions(eps,&nev,NULL,NULL);
    110:   EPSGetInterval(eps,&int0,&int1);
    111:   PetscPrintf(PETSC_COMM_WORLD," Found %D eigenvalues in interval [%g,%g]\n",nev,(double)int0,(double)int1);

    113:   EPSErrorView(eps,EPS_ERROR_ABSOLUTE,NULL);

    115:   EPSDestroy(&eps);
    116:   MatDestroy(&A);
    117:   MatDestroy(&B);
    118:   SlepcFinalize();
    119:   return ierr;
    120: }

    122: /*TEST

    124:    build:
    125:       requires: blzpack

    127:    test:
    128:       suffix: 1
    129:       requires: blzpack

    131: TEST*/