Date: 2024-12-02T08:57:12+00:00

Actual source code: ex55.c
slepc-3.22.2 2024-12-02
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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[] = "Eigenvalue problem with Bethe-Salpeter structure.\n\n"
     12:   "The command line options are:\n"
     13:   "  -n <n>, where <n> = dimension of the blocks.\n\n";

     15: #include <slepceps.h>

     17: /*
     18:    This example computes eigenvalues of a matrix

     20:         H = [  R    C
     21:               -C^H -R^T ],

     23:    where R is Hermitian and C is complex symmetric. In particular, R and C have the
     24:    following Toeplitz structure:

     26:         R = pentadiag{a,b,c,conj(b),conj(a)}
     27:         C = tridiag{b,d,b}

     29:    where a,b,d are complex scalars, and c is real.
     30: */

     32: int main(int argc,char **argv)
     33: {
     34:   Mat            H,R,C;      /* problem matrices */
     35:   EPS            eps;        /* eigenproblem solver context */
     36:   PetscScalar    a,b,c,d;
     37:   PetscReal      lev;
     38:   PetscInt       n=24,Istart,Iend,i,nconv;
     39:   PetscBool      terse,checkorthog;
     40:   Vec            t,*x,*y;

     42:   PetscFunctionBeginUser;
     43:   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));

     45:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
     46:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nBethe-Salpeter eigenproblem, n=%" PetscInt_FMT "\n\n",n));

     48:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     49:                Compute the problem matrices R and C
     50:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     52: #if defined(PETSC_USE_COMPLEX)
     53:   a = PetscCMPLX(-0.1,0.2);
     54:   b = PetscCMPLX(1.0,0.5);
     55:   d = PetscCMPLX(2.0,0.2);
     56: #else
     57:   a = -0.1;
     58:   b = 1.0;
     59:   d = 2.0;
     60: #endif
     61:   c = 4.5;

     63:   PetscCall(MatCreate(PETSC_COMM_WORLD,&R));
     64:   PetscCall(MatSetSizes(R,PETSC_DECIDE,PETSC_DECIDE,n,n));
     65:   PetscCall(MatSetFromOptions(R));

     67:   PetscCall(MatCreate(PETSC_COMM_WORLD,&C));
     68:   PetscCall(MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,n,n));
     69:   PetscCall(MatSetFromOptions(C));

     71:   PetscCall(MatGetOwnershipRange(R,&Istart,&Iend));
     72:   for (i=Istart;i<Iend;i++) {
     73:     if (i>1) PetscCall(MatSetValue(R,i,i-2,a,INSERT_VALUES));
     74:     if (i>0) PetscCall(MatSetValue(R,i,i-1,b,INSERT_VALUES));
     75:     PetscCall(MatSetValue(R,i,i,c,INSERT_VALUES));
     76:     if (i<n-1) PetscCall(MatSetValue(R,i,i+1,PetscConj(b),INSERT_VALUES));
     77:     if (i<n-2) PetscCall(MatSetValue(R,i,i+2,PetscConj(a),INSERT_VALUES));
     78:   }

     80:   PetscCall(MatGetOwnershipRange(C,&Istart,&Iend));
     81:   for (i=Istart;i<Iend;i++) {
     82:     if (i>0) PetscCall(MatSetValue(C,i,i-1,b,INSERT_VALUES));
     83:     PetscCall(MatSetValue(C,i,i,d,INSERT_VALUES));
     84:     if (i<n-1) PetscCall(MatSetValue(C,i,i+1,b,INSERT_VALUES));
     85:   }

     87:   PetscCall(MatAssemblyBegin(R,MAT_FINAL_ASSEMBLY));
     88:   PetscCall(MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY));
     89:   PetscCall(MatAssemblyEnd(R,MAT_FINAL_ASSEMBLY));
     90:   PetscCall(MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY));

     92:   PetscCall(MatCreateBSE(R,C,&H));

     94:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     95:                 Create the eigensolver and set various options
     96:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     98:   PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));
     99:   PetscCall(EPSSetOperators(eps,H,NULL));
    100:   PetscCall(EPSSetProblemType(eps,EPS_BSE));
    101:   PetscCall(EPSSetFromOptions(eps));

    103:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    104:                  Solve the eigensystem and display solution
    105:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    107:   PetscCall(EPSSolve(eps));

    109:   /* show detailed info unless -terse option is given by user */
    110:   PetscCall(PetscOptionsHasName(NULL,NULL,"-terse",&terse));
    111:   if (terse) PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL));
    112:   else {
    113:     PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL));
    114:     PetscCall(EPSConvergedReasonView(eps,PETSC_VIEWER_STDOUT_WORLD));
    115:     PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD));
    116:     PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
    117:   }

    119:   /* check bi-orthogonality */
    120:   PetscCall(PetscOptionsHasName(NULL,NULL,"-checkorthog",&checkorthog));
    121:   PetscCall(EPSGetConverged(eps,&nconv));
    122:   if (checkorthog && nconv>0) {
    123:     PetscCall(MatCreateVecs(H,&t,NULL));
    124:     PetscCall(VecDuplicateVecs(t,nconv,&x));
    125:     PetscCall(VecDuplicateVecs(t,nconv,&y));
    126:     for (i=0;i<nconv;i++) {
    127:       PetscCall(EPSGetEigenvector(eps,i,x[i],NULL));
    128:       PetscCall(EPSGetLeftEigenvector(eps,i,y[i],NULL));
    129:     }
    130:     PetscCall(VecCheckOrthogonality(x,nconv,y,nconv,NULL,NULL,&lev));
    131:     if (lev<100*PETSC_MACHINE_EPSILON) PetscCall(PetscPrintf(PETSC_COMM_WORLD," Level of bi-orthogonality of eigenvectors < 100*eps\n\n"));
    132:     else PetscCall(PetscPrintf(PETSC_COMM_WORLD," Level of bi-orthogonality of eigenvectors: %g\n\n",(double)lev));
    133:     PetscCall(VecDestroy(&t));
    134:     PetscCall(VecDestroyVecs(nconv,&x));
    135:     PetscCall(VecDestroyVecs(nconv,&y));
    136:   }

    138:   PetscCall(EPSDestroy(&eps));
    139:   PetscCall(MatDestroy(&R));
    140:   PetscCall(MatDestroy(&C));
    141:   PetscCall(MatDestroy(&H));
    142:   PetscCall(SlepcFinalize());
    143:   return 0;
    144: }

    146: /*TEST

    148:    testset:
    149:       args: -eps_nev 4 -eps_ncv 16 -eps_krylovschur_bse_type {{shao gruning projectedbse}} -terse -checkorthog
    150:       filter: sed -e "s/17496/17495/g" | sed -e "s/38566/38567/g"
    151:       nsize: {{1 2}}
    152:       test:
    153:          suffix: 1
    154:          requires: complex
    155:       test:
    156:          suffix: 1_real
    157:          requires: !complex

    159:    testset:
    160:       args: -eps_nev 4 -eps_ncv 16 -eps_krylovschur_bse_type {{shao gruning projectedbse}} -st_type sinvert -terse
    161:       filter: sed -e "s/17496/17495/g" | sed -e "s/38566/38567/g"
    162:       test:
    163:          suffix: 1_sinvert
    164:          requires: complex
    165:       test:
    166:          nsize: 4
    167:          args: -mat_type scalapack
    168:          suffix: 1_sinvert_scalapack
    169:          requires: complex scalapack
    170:          output_file: output/ex55_1_sinvert.out
    171:       test:
    172:          suffix: 1_real_sinvert
    173:          requires: !complex
    174:       test:
    175:          nsize: 4
    176:          args: -mat_type scalapack
    177:          suffix: 1_real_sinvert_scalapack
    178:          requires: !complex scalapack
    179:          output_file: output/ex55_1_real_sinvert.out

    181: TEST*/