Actual source code: test12.c

slepc-3.13.1 2020-04-12
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  1: /*
  2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  4:    Copyright (c) 2002-2020, 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 some NLEIGS interface functions.\n\n"
 12:   "Based on ex27.c. The command line options are:\n"
 13:   "  -n <n>, where <n> = matrix dimension.\n";

 15: /*
 16:    Solve T(lambda)x=0 using NLEIGS solver
 17:       with T(lambda) = -D+sqrt(lambda)*I
 18:       where D is the Laplacian operator in 1 dimension
 19:       and with the interpolation interval [.01,16]
 20: */

 22: #include <slepcnep.h>

 24: /*
 25:    User-defined routines
 26: */
 27: PetscErrorCode ComputeSingularities(NEP,PetscInt*,PetscScalar*,void*);

 29: int main(int argc,char **argv)
 30: {
 31:   NEP            nep;             /* nonlinear eigensolver context */
 32:   Mat            A[2];
 33:   PetscInt       n=100,Istart,Iend,i,ns,nsin;
 35:   PetscBool      terse,fb;
 36:   RG             rg;
 37:   FN             f[2];
 38:   PetscScalar    coeffs,shifts[]={1.06,1.1,1.12,1.15},*rkshifts,val;
 39:   PetscErrorCode (*fsing)(NEP,PetscInt*,PetscScalar*,void*);

 41:   SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
 42:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
 43:   PetscPrintf(PETSC_COMM_WORLD,"\nSquare root eigenproblem, n=%D\n\n",n);

 45:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 46:      Create nonlinear eigensolver and set some options
 47:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 49:   NEPCreate(PETSC_COMM_WORLD,&nep);
 50:   NEPSetType(nep,NEPNLEIGS);
 51:   NEPNLEIGSSetSingularitiesFunction(nep,ComputeSingularities,NULL);
 52:   NEPGetRG(nep,&rg);
 53:   RGSetType(rg,RGINTERVAL);
 54: #if defined(PETSC_USE_COMPLEX)
 55:   RGIntervalSetEndpoints(rg,0.01,16.0,-0.001,0.001);
 56: #else
 57:   RGIntervalSetEndpoints(rg,0.01,16.0,0,0);
 58: #endif
 59:   NEPSetTarget(nep,1.1);

 61:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 62:      Define the nonlinear problem in split form
 63:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 65:   /* Create matrices */
 66:   MatCreate(PETSC_COMM_WORLD,&A[0]);
 67:   MatSetSizes(A[0],PETSC_DECIDE,PETSC_DECIDE,n,n);
 68:   MatSetFromOptions(A[0]);
 69:   MatSetUp(A[0]);
 70:   MatGetOwnershipRange(A[0],&Istart,&Iend);
 71:   for (i=Istart;i<Iend;i++) {
 72:     if (i>0) { MatSetValue(A[0],i,i-1,1.0,INSERT_VALUES); }
 73:     if (i<n-1) { MatSetValue(A[0],i,i+1,1.0,INSERT_VALUES); }
 74:     MatSetValue(A[0],i,i,-2.0,INSERT_VALUES);
 75:   }
 76:   MatAssemblyBegin(A[0],MAT_FINAL_ASSEMBLY);
 77:   MatAssemblyEnd(A[0],MAT_FINAL_ASSEMBLY);

 79:   MatCreate(PETSC_COMM_WORLD,&A[1]);
 80:   MatSetSizes(A[1],PETSC_DECIDE,PETSC_DECIDE,n,n);
 81:   MatSetFromOptions(A[1]);
 82:   MatSetUp(A[1]);
 83:   MatAssemblyBegin(A[1],MAT_FINAL_ASSEMBLY);
 84:   MatAssemblyEnd(A[1],MAT_FINAL_ASSEMBLY);
 85:   MatShift(A[1],1.0);

 87:   /* Define functions */
 88:   FNCreate(PETSC_COMM_WORLD,&f[0]);
 89:   FNSetType(f[0],FNRATIONAL);
 90:   coeffs = 1.0;
 91:   FNRationalSetNumerator(f[0],1,&coeffs);
 92:   FNCreate(PETSC_COMM_WORLD,&f[1]);
 93:   FNSetType(f[1],FNSQRT);
 94:   NEPSetSplitOperator(nep,2,A,f,SUBSET_NONZERO_PATTERN);

 96:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 97:                         Set some options
 98:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

100:   NEPNLEIGSSetFullBasis(nep,PETSC_FALSE);
101:   NEPNLEIGSSetRKShifts(nep,4,shifts);
102:   NEPSetFromOptions(nep);

104:   NEPNLEIGSGetFullBasis(nep,&fb);
105:   PetscPrintf(PETSC_COMM_WORLD," Using full basis = %s\n",fb?"true":"false");
106:   NEPNLEIGSGetRKShifts(nep,&ns,&rkshifts);
107:   if (ns) {
108:     PetscPrintf(PETSC_COMM_WORLD," Using %d RK shifts =",ns);
109:     for (i=0;i<ns;i++) {
110:       PetscPrintf(PETSC_COMM_WORLD," %g",(double)PetscRealPart(rkshifts[i]));
111:     }
112:     PetscPrintf(PETSC_COMM_WORLD,"\n");
113:     PetscFree(rkshifts);
114:   }
115:   NEPNLEIGSGetSingularitiesFunction(nep,&fsing,NULL);
116:   nsin = 1;
117:   (*fsing)(nep,&nsin,&val,NULL);
118:   PetscPrintf(PETSC_COMM_WORLD," First returned singularity = %g\n",(double)PetscRealPart(val));

120:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
121:                       Solve the eigensystem
122:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
123:   NEPSolve(nep);

125:   /* show detailed info unless -terse option is given by user */
126:   PetscOptionsHasName(NULL,NULL,"-terse",&terse);
127:   if (terse) {
128:     NEPErrorView(nep,NEP_ERROR_BACKWARD,NULL);
129:   } else {
130:     PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
131:     NEPReasonView(nep,PETSC_VIEWER_STDOUT_WORLD);
132:     NEPErrorView(nep,NEP_ERROR_BACKWARD,PETSC_VIEWER_STDOUT_WORLD);
133:     PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
134:   }
135:   NEPDestroy(&nep);
136:   MatDestroy(&A[0]);
137:   MatDestroy(&A[1]);
138:   FNDestroy(&f[0]);
139:   FNDestroy(&f[1]);
140:   SlepcFinalize();
141:   return ierr;
142: }

144: /* ------------------------------------------------------------------- */
145: /*
146:    ComputeSingularities - Computes maxnp points (at most) in the complex plane where
147:    the function T(.) is not analytic.

149:    In this case, we discretize the singularity region (-inf,0)~(-10e+6,-10e-6)
150: */
151: PetscErrorCode ComputeSingularities(NEP nep,PetscInt *maxnp,PetscScalar *xi,void *pt)
152: {
153:   PetscReal h;
154:   PetscInt  i;

157:   h = 11.0/(*maxnp-1);
158:   xi[0] = -1e-5; xi[*maxnp-1] = -1e+6;
159:   for (i=1;i<*maxnp-1;i++) xi[i] = -PetscPowReal(10,-5+h*i);
160:   return(0);
161: }

163: /*TEST

165:    test:
166:       suffix: 1
167:       args: -nep_nev 3 -nep_nleigs_interpolation_degree 90 -terse -nep_view
168:       requires: double
169:       filter: grep -v tolerance

171: TEST*/