Actual source code: test24.c

slepc-3.11.2 2019-07-30
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  1: /*
  2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  4:    Copyright (c) 2002-2019, 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[] = "Eigenproblem for the 1-D Laplacian with constraints. "
 12:   "Based on ex1.\n"
 13:   "The command line options are:\n"
 14:   "  -n <n>, where <n> = number of grid subdivisions = matrix dimension.\n\n";

 16: #include <slepceps.h>

 18: int main(int argc,char **argv)
 19: {
 20:   Mat            A;
 21:   EPS            eps;
 22:   EPSType        type;
 23:   Vec            *vi=NULL,*vc=NULL,t;
 24:   PetscInt       n=30,nev=4,i,j,Istart,Iend,nini=0,ncon=0,bs;
 25:   PetscReal      alpha,beta,restart;
 26:   PetscBool      flg,lock;

 29:   SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
 30:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
 31:   PetscOptionsGetInt(NULL,NULL,"-nini",&nini,NULL);
 32:   PetscOptionsGetInt(NULL,NULL,"-ncon",&ncon,NULL);
 33:   PetscPrintf(PETSC_COMM_WORLD,"\n1-D Laplacian Eigenproblem, n=%D nini=%D ncon=%D\n\n",n,nini,ncon);

 35:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 36:      Compute the operator matrix that defines the eigensystem, Ax=kx
 37:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 39:   MatCreate(PETSC_COMM_WORLD,&A);
 40:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);
 41:   MatSetFromOptions(A);
 42:   MatSetUp(A);

 44:   MatGetOwnershipRange(A,&Istart,&Iend);
 45:   for (i=Istart;i<Iend;i++) {
 46:     if (i>0) { MatSetValue(A,i,i-1,-1.0,INSERT_VALUES); }
 47:     if (i<n-1) { MatSetValue(A,i,i+1,-1.0,INSERT_VALUES); }
 48:     MatSetValue(A,i,i,2.0,INSERT_VALUES);
 49:   }
 50:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 51:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

 53:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 54:                 Create the eigensolver and set various options
 55:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 56:   EPSCreate(PETSC_COMM_WORLD,&eps);
 57:   EPSSetOperators(eps,A,NULL);
 58:   EPSSetProblemType(eps,EPS_HEP);
 59:   EPSSetType(eps,EPSLOBPCG);
 60:   EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL);
 61:   EPSSetConvergenceTest(eps,EPS_CONV_ABS);
 62:   EPSSetDimensions(eps,nev,PETSC_DEFAULT,PETSC_DEFAULT);
 63:   EPSLOBPCGSetBlockSize(eps,nev);
 64:   EPSLOBPCGSetRestart(eps,0.7);
 65:   EPSSetTolerances(eps,1e-8,1200);
 66:   EPSSetFromOptions(eps);

 68:   MatCreateVecs(A,&t,NULL);
 69:   if (nini) {
 70:     VecDuplicateVecs(t,nini,&vi);
 71:     for (i=0;i<nini;i++) {
 72:       VecSetRandom(vi[i],NULL);
 73:     }
 74:     EPSSetInitialSpace(eps,nini,vi);
 75:   }
 76:   if (ncon) {   /* constraints are exact eigenvectors of lowest eigenvalues */
 77:     alpha = PETSC_PI/(n+1);
 78:     beta  = PetscSqrtReal(2.0/(n+1));
 79:     VecDuplicateVecs(t,ncon,&vc);
 80:     for (i=0;i<ncon;i++) {
 81:       for (j=0;j<n;j++) {
 82:         VecSetValue(vc[i],j,PetscSinReal(alpha*(j+1)*(i+1))*beta,INSERT_VALUES);
 83:       }
 84:       VecAssemblyBegin(vc[i]);
 85:       VecAssemblyEnd(vc[i]);
 86:     }
 87:     EPSSetDeflationSpace(eps,ncon,vc);
 88:   }

 90:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 91:                       Solve the eigensystem
 92:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 94:   EPSSolve(eps);
 95:   EPSGetType(eps,&type);
 96:   PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n",type);
 97:   PetscObjectTypeCompare((PetscObject)eps,EPSLOBPCG,&flg);
 98:   if (flg) {
 99:     EPSLOBPCGGetLocking(eps,&lock);
100:     if (lock) { PetscPrintf(PETSC_COMM_WORLD," Using soft locking\n"); }
101:     EPSLOBPCGGetRestart(eps,&restart);
102:     PetscPrintf(PETSC_COMM_WORLD," LOBPCG Restart parameter=%.4g\n",(double)restart);
103:     EPSLOBPCGGetBlockSize(eps,&bs);
104:     PetscPrintf(PETSC_COMM_WORLD," LOBPCG Block size=%D\n",bs);
105:   }

107:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
108:                     Display solution and clean up
109:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

111:   EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
112:   EPSDestroy(&eps);
113:   MatDestroy(&A);
114:   VecDestroyVecs(nini,&vi);
115:   VecDestroyVecs(ncon,&vc);
116:   VecDestroy(&t);
117:   SlepcFinalize();
118:   return ierr;
119: }

121: /*TEST

123:    testset:
124:       args: -ncon 2
125:       output_file: output/test24_1.out
126:       test:
127:          suffix: 1
128:          requires: !single
129:       test:
130:          suffix: 2_cuda
131:          args: -mat_type aijcusparse
132:          requires: cuda !single

134: TEST*/