Date: 2016-03-29T14:57:32+00:00

Actual source code: test8.c
slepc-3.6.3 2016-03-29
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2015, Universitat Politecnica de Valencia, Spain

      6:    This file is part of SLEPc.

      8:    SLEPc is free software: you can redistribute it and/or modify it under  the
      9:    terms of version 3 of the GNU Lesser General Public License as published by
     10:    the Free Software Foundation.

     12:    SLEPc  is  distributed in the hope that it will be useful, but WITHOUT  ANY
     13:    WARRANTY;  without even the implied warranty of MERCHANTABILITY or  FITNESS
     14:    FOR  A  PARTICULAR PURPOSE. See the GNU Lesser General Public  License  for
     15:    more details.

     17:    You  should have received a copy of the GNU Lesser General  Public  License
     18:    along with SLEPc. If not, see <http://www.gnu.org/licenses/>.
     19:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     20: */

     22: static char help[] = "Test BV orthogonalization with selected columns.\n\n";

     24: #include <slepcbv.h>

     28: int main(int argc,char **argv)
     29: {
     31:   BV             X;
     32:   Vec            v,t,z;
     33:   PetscInt       i,j,n=20,k=8;
     34:   PetscViewer    view;
     35:   PetscBool      verbose,*which;
     36:   PetscReal      norm;
     37:   PetscScalar    alpha,*pz;

     39:   SlepcInitialize(&argc,&argv,(char*)0,help);
     40:   PetscOptionsGetInt(NULL,"-n",&n,NULL);
     41:   PetscOptionsGetInt(NULL,"-k",&k,NULL);
     42:   PetscOptionsHasName(NULL,"-verbose",&verbose);
     43:   PetscPrintf(PETSC_COMM_WORLD,"Test BV orthogonalization with selected columns of length %D.\n",n);

     45:   /* Create template vector */
     46:   VecCreate(PETSC_COMM_WORLD,&t);
     47:   VecSetSizes(t,PETSC_DECIDE,n);
     48:   VecSetFromOptions(t);

     50:   /* Create BV object X */
     51:   BVCreate(PETSC_COMM_WORLD,&X);
     52:   PetscObjectSetName((PetscObject)X,"X");
     53:   BVSetSizesFromVec(X,t,k);
     54:   BVSetOrthogonalization(X,BV_ORTHOG_MGS,BV_ORTHOG_REFINE_IFNEEDED,PETSC_DEFAULT,BV_ORTHOG_BLOCK_GS);
     55:   BVSetFromOptions(X);

     57:   /* Set up viewer */
     58:   PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&view);
     59:   if (verbose) {
     60:     PetscViewerPushFormat(view,PETSC_VIEWER_ASCII_MATLAB);
     61:   }

     63:   /* Fill X entries */
     64:   for (j=0;j<k;j++) {
     65:     BVGetColumn(X,j,&v);
     66:     VecSet(v,0.0);
     67:     for (i=0;i<=n/2;i++) {
     68:       if (i+j<n) {
     69:         alpha = (3.0*i+j-2)/(2*(i+j+1));
     70:         VecSetValue(v,i+j,alpha,INSERT_VALUES);
     71:       }
     72:     }
     73:     VecAssemblyBegin(v);
     74:     VecAssemblyEnd(v);
     75:     BVRestoreColumn(X,j,&v);
     76:   }
     77:   if (verbose) {
     78:     BVView(X,view);
     79:   }

     81:   /* Orthonormalize first k-1 columns */
     82:   for (j=0;j<k-1;j++) {
     83:     BVOrthogonalizeColumn(X,j,NULL,&norm,NULL);
     84:     alpha = 1.0/norm;
     85:     BVScaleColumn(X,j,alpha);
     86:   }
     87:   if (verbose) {
     88:     BVView(X,view);
     89:   }

     91:   /* Select odd columns and orthogonalize last column against those only */
     92:   PetscMalloc1(k,&which);
     93:   for (i=0;i<k;i++) which[i] = (i%2)? PETSC_TRUE: PETSC_FALSE;
     94:   BVOrthogonalizeSomeColumn(X,k-1,which,NULL,NULL,NULL);
     95:   PetscFree(which);
     96:   if (verbose) {
     97:     BVView(X,view);
     98:   }

    100:   /* Check orthogonality */
    101:   PetscPrintf(PETSC_COMM_WORLD,"Orthogonalization coefficients:\n");
    102:   VecCreateSeq(PETSC_COMM_SELF,k-1,&z);
    103:   PetscObjectSetName((PetscObject)z,"z");
    104:   VecGetArray(z,&pz);
    105:   BVDotColumn(X,k-1,pz);
    106:   for (i=0;i<k-1;i++) {
    107:     if (PetscAbsScalar(pz[i])<PETSC_MACHINE_EPSILON) pz[i]=0.0;
    108:   }
    109:   VecRestoreArray(z,&pz);
    110:   VecView(z,view);
    111:   VecDestroy(&z);

    113:   BVDestroy(&X);
    114:   VecDestroy(&t);
    115:   SlepcFinalize();
    116:   return 0;
    117: }