Actual source code: test9.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[] = "Test DSGHEP.\n\n";

 13: #include <slepcds.h>

 15: /*
 16:    Compute the norm of the j-th column of matrix mat in ds
 17:  */
 18: PetscErrorCode ComputeNorm(DS ds,DSMatType mat,PetscInt j,PetscReal *onrm)
 19: {
 21:   PetscScalar    *X;
 22:   PetscReal      aux,nrm=0.0;
 23:   PetscInt       i,n,ld;

 26:   DSGetLeadingDimension(ds,&ld);
 27:   DSGetDimensions(ds,&n,NULL,NULL,NULL,NULL);
 28:   DSGetArray(ds,mat,&X);
 29:   for (i=0;i<n;i++) {
 30:     aux = PetscAbsScalar(X[i+j*ld]);
 31:     nrm += aux*aux;
 32:   }
 33:   DSRestoreArray(ds,mat,&X);
 34:   *onrm = PetscSqrtReal(nrm);
 35:   return(0);
 36: }

 38: int main(int argc,char **argv)
 39: {
 41:   DS             ds;
 42:   SlepcSC        sc;
 43:   PetscReal      re;
 44:   PetscScalar    *A,*B,*eig;
 45:   PetscReal      nrm;
 46:   PetscInt       i,j,n=10,ld;
 47:   PetscViewer    viewer;
 48:   PetscBool      verbose;

 50:   SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
 51:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
 52:   PetscPrintf(PETSC_COMM_WORLD,"Solve a System of type GHEP - dimension %D.\n",n);
 53:   PetscOptionsHasName(NULL,NULL,"-verbose",&verbose);

 55:   /* Create DS object */
 56:   DSCreate(PETSC_COMM_WORLD,&ds);
 57:   DSSetType(ds,DSGHEP);
 58:   DSSetFromOptions(ds);
 59:   ld = n+2;  /* test leading dimension larger than n */
 60:   DSAllocate(ds,ld);
 61:   DSSetDimensions(ds,n,0,0,0);

 63:   /* Set up viewer */
 64:   PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer);
 65:   PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL);
 66:   DSView(ds,viewer);
 67:   PetscViewerPopFormat(viewer);
 68:   if (verbose) {
 69:     PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB);
 70:   }

 72:   /* Fill with a symmetric Toeplitz matrix */
 73:   DSGetArray(ds,DS_MAT_A,&A);
 74:   DSGetArray(ds,DS_MAT_B,&B);
 75:   for (i=0;i<n;i++) A[i+i*ld]=2.0;
 76:   for (j=1;j<3;j++) {
 77:     for (i=0;i<n-j;i++) { A[i+(i+j)*ld]=1.0; A[(i+j)+i*ld]=1.0; }
 78:   }
 79:   for (j=1;j<3;j++) { A[0+j*ld]=-1.0*(j+2); A[j+0*ld]=-1.0*(j+2); }
 80:   /* Diagonal matrix */
 81:   for (i=0;i<n;i++) B[i+i*ld]=0.1*(i+1);
 82:   DSRestoreArray(ds,DS_MAT_A,&A);
 83:   DSRestoreArray(ds,DS_MAT_B,&B);
 84:   DSSetState(ds,DS_STATE_RAW);
 85:   if (verbose) {
 86:     PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n");
 87:     DSView(ds,viewer);
 88:   }

 90:   /* Solve */
 91:   PetscMalloc1(n,&eig);
 92:   PetscNew(&sc);
 93:   sc->comparison    = SlepcCompareLargestMagnitude;
 94:   sc->comparisonctx = NULL;
 95:   sc->map           = NULL;
 96:   sc->mapobj        = NULL;
 97:   DSSetSlepcSC(ds,sc);
 98:   DSSolve(ds,eig,NULL);
 99:   DSSort(ds,eig,NULL,NULL,NULL,NULL);
100:   if (verbose) {
101:     PetscPrintf(PETSC_COMM_WORLD,"After solve - - - - - - - - -\n");
102:     DSView(ds,viewer);
103:   }

105:   /* Print eigenvalues */
106:   PetscPrintf(PETSC_COMM_WORLD,"Computed eigenvalues =\n");
107:   for (i=0;i<n;i++) {
108:     re = PetscRealPart(eig[i]);
109:     PetscViewerASCIIPrintf(viewer,"  %.5f\n",(double)re);
110:   }

112:   /* Eigenvectors */
113:   DSVectors(ds,DS_MAT_X,NULL,NULL);  /* all eigenvectors */
114:   ComputeNorm(ds,DS_MAT_X,0,&nrm);
115:   PetscPrintf(PETSC_COMM_WORLD,"Norm of 1st vector = %.3f\n",(double)nrm);
116:   if (verbose) {
117:     PetscPrintf(PETSC_COMM_WORLD,"After vectors - - - - - - - - -\n");
118:     DSView(ds,viewer);
119:   }

121:   PetscFree(eig);
122:   PetscFree(sc);
123:   DSDestroy(&ds);
124:   SlepcFinalize();
125:   return ierr;
126: }

128: /*TEST

130:    test:
131:       suffix: 1
132:       requires: !single

134: TEST*/