Actual source code: test12.c
slepc-3.17.0 2022-03-31
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[] = "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;
34: PetscBool terse,fb;
35: RG rg;
36: FN f[2];
37: PetscScalar coeffs,shifts[]={1.06,1.1,1.12,1.15},*rkshifts,val;
38: PetscErrorCode (*fsing)(NEP,PetscInt*,PetscScalar*,void*);
40: SlepcInitialize(&argc,&argv,(char*)0,help);
41: PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
42: PetscPrintf(PETSC_COMM_WORLD,"\nSquare root eigenproblem, n=%" PetscInt_FMT "\n\n",n);
44: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
45: Create nonlinear eigensolver and set some options
46: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
48: NEPCreate(PETSC_COMM_WORLD,&nep);
49: NEPSetType(nep,NEPNLEIGS);
50: NEPNLEIGSSetSingularitiesFunction(nep,ComputeSingularities,NULL);
51: NEPGetRG(nep,&rg);
52: RGSetType(rg,RGINTERVAL);
53: #if defined(PETSC_USE_COMPLEX)
54: RGIntervalSetEndpoints(rg,0.01,16.0,-0.001,0.001);
55: #else
56: RGIntervalSetEndpoints(rg,0.01,16.0,0,0);
57: #endif
58: NEPSetTarget(nep,1.1);
60: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
61: Define the nonlinear problem in split form
62: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
64: /* Create matrices */
65: MatCreate(PETSC_COMM_WORLD,&A[0]);
66: MatSetSizes(A[0],PETSC_DECIDE,PETSC_DECIDE,n,n);
67: MatSetFromOptions(A[0]);
68: MatSetUp(A[0]);
69: MatGetOwnershipRange(A[0],&Istart,&Iend);
70: for (i=Istart;i<Iend;i++) {
71: if (i>0) MatSetValue(A[0],i,i-1,1.0,INSERT_VALUES);
72: if (i<n-1) MatSetValue(A[0],i,i+1,1.0,INSERT_VALUES);
73: MatSetValue(A[0],i,i,-2.0,INSERT_VALUES);
74: }
75: MatAssemblyBegin(A[0],MAT_FINAL_ASSEMBLY);
76: MatAssemblyEnd(A[0],MAT_FINAL_ASSEMBLY);
78: MatCreateConstantDiagonal(PETSC_COMM_WORLD,PETSC_DECIDE,PETSC_DECIDE,n,n,1.0,&A[1]);
80: /* Define functions */
81: FNCreate(PETSC_COMM_WORLD,&f[0]);
82: FNSetType(f[0],FNRATIONAL);
83: coeffs = 1.0;
84: FNRationalSetNumerator(f[0],1,&coeffs);
85: FNCreate(PETSC_COMM_WORLD,&f[1]);
86: FNSetType(f[1],FNSQRT);
87: NEPSetSplitOperator(nep,2,A,f,SUBSET_NONZERO_PATTERN);
89: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
90: Set some options
91: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
93: NEPNLEIGSSetFullBasis(nep,PETSC_FALSE);
94: NEPNLEIGSSetRKShifts(nep,4,shifts);
95: NEPSetFromOptions(nep);
97: NEPNLEIGSGetFullBasis(nep,&fb);
98: PetscPrintf(PETSC_COMM_WORLD," Using full basis = %s\n",fb?"true":"false");
99: NEPNLEIGSGetRKShifts(nep,&ns,&rkshifts);
100: if (ns) {
101: PetscPrintf(PETSC_COMM_WORLD," Using %" PetscInt_FMT " RK shifts =",ns);
102: for (i=0;i<ns;i++) PetscPrintf(PETSC_COMM_WORLD," %g",(double)PetscRealPart(rkshifts[i]));
103: PetscPrintf(PETSC_COMM_WORLD,"\n");
104: PetscFree(rkshifts);
105: }
106: NEPNLEIGSGetSingularitiesFunction(nep,&fsing,NULL);
107: nsin = 1;
108: (*fsing)(nep,&nsin,&val,NULL);
109: PetscPrintf(PETSC_COMM_WORLD," First returned singularity = %g\n",(double)PetscRealPart(val));
111: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
112: Solve the eigensystem
113: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
114: NEPSolve(nep);
116: /* show detailed info unless -terse option is given by user */
117: PetscOptionsHasName(NULL,NULL,"-terse",&terse);
118: if (terse) NEPErrorView(nep,NEP_ERROR_BACKWARD,NULL);
119: else {
120: PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
121: NEPConvergedReasonView(nep,PETSC_VIEWER_STDOUT_WORLD);
122: NEPErrorView(nep,NEP_ERROR_BACKWARD,PETSC_VIEWER_STDOUT_WORLD);
123: PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
124: }
125: NEPDestroy(&nep);
126: MatDestroy(&A[0]);
127: MatDestroy(&A[1]);
128: FNDestroy(&f[0]);
129: FNDestroy(&f[1]);
130: SlepcFinalize();
131: return 0;
132: }
134: /* ------------------------------------------------------------------- */
135: /*
136: ComputeSingularities - Computes maxnp points (at most) in the complex plane where
137: the function T(.) is not analytic.
139: In this case, we discretize the singularity region (-inf,0)~(-10e+6,-10e-6)
140: */
141: PetscErrorCode ComputeSingularities(NEP nep,PetscInt *maxnp,PetscScalar *xi,void *pt)
142: {
143: PetscReal h;
144: PetscInt i;
147: h = 11.0/(*maxnp-1);
148: xi[0] = -1e-5; xi[*maxnp-1] = -1e+6;
149: for (i=1;i<*maxnp-1;i++) xi[i] = -PetscPowReal(10,-5+h*i);
150: PetscFunctionReturn(0);
151: }
153: /*TEST
155: test:
156: suffix: 1
157: args: -nep_nev 3 -nep_nleigs_interpolation_degree 20 -terse -nep_view
158: requires: double
159: filter: grep -v tolerance | sed -e "s/[+-]0\.0*i//g"
161: TEST*/