Actual source code: test15.c
slepc-3.21.1 2024-04-26
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[] = "Illustrates the use of a user-defined stopping test.\n\n"
12: "This is based on ex22.\n"
13: "The command line options are:\n"
14: " -n <n>, where <n> = number of grid subdivisions.\n"
15: " -tau <tau>, where <tau> is the delay parameter.\n\n";
17: /*
18: Solve parabolic partial differential equation with time delay tau
20: u_t = u_xx + a*u(t) + b*u(t-tau)
21: u(0,t) = u(pi,t) = 0
23: with a = 20 and b(x) = -4.1+x*(1-exp(x-pi)).
25: Discretization leads to a DDE of dimension n
27: -u' = A*u(t) + B*u(t-tau)
29: which results in the nonlinear eigenproblem
31: (-lambda*I + A + exp(-tau*lambda)*B)*u = 0
32: */
34: #include <slepcnep.h>
36: /*
37: User-defined routines
38: */
39: PetscErrorCode MyStoppingTest(NEP,PetscInt,PetscInt,PetscInt,PetscInt,NEPConvergedReason*,void*);
41: typedef struct {
42: PetscInt lastnconv; /* last value of nconv; used in stopping test */
43: PetscInt nreps; /* number of repetitions of nconv; used in stopping test */
44: } CTX_DELAY;
46: int main(int argc,char **argv)
47: {
48: NEP nep;
49: Mat Id,A,B;
50: FN f1,f2,f3;
51: RG rg;
52: CTX_DELAY *ctx;
53: Mat mats[3];
54: FN funs[3];
55: PetscScalar coeffs[2],b;
56: PetscInt n=128,Istart,Iend,i,mpd;
57: PetscReal tau=0.001,h,a=20,xi;
58: PetscBool terse;
59: PetscViewer viewer;
61: PetscFunctionBeginUser;
62: PetscCall(SlepcInitialize(&argc,&argv,(char*)0,help));
63: PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
64: PetscCall(PetscOptionsGetReal(NULL,NULL,"-tau",&tau,NULL));
65: PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\n1-D Delay Eigenproblem, n=%" PetscInt_FMT ", tau=%g\n\n",n,(double)tau));
66: h = PETSC_PI/(PetscReal)(n+1);
68: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
69: Create nonlinear eigensolver context
70: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
72: PetscCall(NEPCreate(PETSC_COMM_WORLD,&nep));
74: /* Identity matrix */
75: PetscCall(MatCreateConstantDiagonal(PETSC_COMM_WORLD,PETSC_DECIDE,PETSC_DECIDE,n,n,1.0,&Id));
76: PetscCall(MatSetOption(Id,MAT_HERMITIAN,PETSC_TRUE));
78: /* A = 1/h^2*tridiag(1,-2,1) + a*I */
79: PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
80: PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n));
81: PetscCall(MatSetFromOptions(A));
82: PetscCall(MatGetOwnershipRange(A,&Istart,&Iend));
83: for (i=Istart;i<Iend;i++) {
84: if (i>0) PetscCall(MatSetValue(A,i,i-1,1.0/(h*h),INSERT_VALUES));
85: if (i<n-1) PetscCall(MatSetValue(A,i,i+1,1.0/(h*h),INSERT_VALUES));
86: PetscCall(MatSetValue(A,i,i,-2.0/(h*h)+a,INSERT_VALUES));
87: }
88: PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY));
89: PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY));
90: PetscCall(MatSetOption(A,MAT_HERMITIAN,PETSC_TRUE));
92: /* B = diag(b(xi)) */
93: PetscCall(MatCreate(PETSC_COMM_WORLD,&B));
94: PetscCall(MatSetSizes(B,PETSC_DECIDE,PETSC_DECIDE,n,n));
95: PetscCall(MatSetFromOptions(B));
96: PetscCall(MatGetOwnershipRange(B,&Istart,&Iend));
97: for (i=Istart;i<Iend;i++) {
98: xi = (i+1)*h;
99: b = -4.1+xi*(1.0-PetscExpReal(xi-PETSC_PI));
100: PetscCall(MatSetValues(B,1,&i,1,&i,&b,INSERT_VALUES));
101: }
102: PetscCall(MatAssemblyBegin(B,MAT_FINAL_ASSEMBLY));
103: PetscCall(MatAssemblyEnd(B,MAT_FINAL_ASSEMBLY));
104: PetscCall(MatSetOption(B,MAT_HERMITIAN,PETSC_TRUE));
106: /* Functions: f1=-lambda, f2=1.0, f3=exp(-tau*lambda) */
107: PetscCall(FNCreate(PETSC_COMM_WORLD,&f1));
108: PetscCall(FNSetType(f1,FNRATIONAL));
109: coeffs[0] = -1.0; coeffs[1] = 0.0;
110: PetscCall(FNRationalSetNumerator(f1,2,coeffs));
112: PetscCall(FNCreate(PETSC_COMM_WORLD,&f2));
113: PetscCall(FNSetType(f2,FNRATIONAL));
114: coeffs[0] = 1.0;
115: PetscCall(FNRationalSetNumerator(f2,1,coeffs));
117: PetscCall(FNCreate(PETSC_COMM_WORLD,&f3));
118: PetscCall(FNSetType(f3,FNEXP));
119: PetscCall(FNSetScale(f3,-tau,1.0));
121: /* Set the split operator */
122: mats[0] = A; funs[0] = f2;
123: mats[1] = Id; funs[1] = f1;
124: mats[2] = B; funs[2] = f3;
125: PetscCall(NEPSetSplitOperator(nep,3,mats,funs,SUBSET_NONZERO_PATTERN));
127: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
128: Customize nonlinear solver; set runtime options
129: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
131: PetscCall(NEPSetType(nep,NEPNLEIGS));
132: PetscCall(NEPGetRG(nep,&rg));
133: PetscCall(RGSetType(rg,RGINTERVAL));
134: #if defined(PETSC_USE_COMPLEX)
135: PetscCall(RGIntervalSetEndpoints(rg,5,20,-0.001,0.001));
136: #else
137: PetscCall(RGIntervalSetEndpoints(rg,5,20,-0.0,0.0));
138: #endif
139: PetscCall(NEPSetTarget(nep,15.0));
140: PetscCall(NEPSetWhichEigenpairs(nep,NEP_TARGET_MAGNITUDE));
142: /*
143: Set solver options. In particular, we must allocate sufficient
144: storage for all eigenpairs that may converge (ncv). This is
145: application-dependent.
146: */
147: mpd = 40;
148: PetscCall(NEPSetDimensions(nep,2*mpd,3*mpd,mpd));
149: PetscCall(NEPSetTolerances(nep,PETSC_DEFAULT,2000));
150: PetscCall(PetscNew(&ctx));
151: ctx->lastnconv = 0;
152: ctx->nreps = 0;
153: PetscCall(NEPSetStoppingTestFunction(nep,MyStoppingTest,(void*)ctx,NULL));
155: PetscCall(NEPSetFromOptions(nep));
157: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
158: Solve the eigensystem
159: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
161: PetscCall(NEPSolve(nep));
163: /* show detailed info unless -terse option is given by user */
164: PetscCall(PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer));
165: PetscCall(PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL));
166: PetscCall(NEPConvergedReasonView(nep,viewer));
167: PetscCall(PetscOptionsHasName(NULL,NULL,"-terse",&terse));
168: if (!terse) PetscCall(NEPErrorView(nep,NEP_ERROR_BACKWARD,viewer));
169: PetscCall(PetscViewerPopFormat(viewer));
171: PetscCall(NEPDestroy(&nep));
172: PetscCall(MatDestroy(&Id));
173: PetscCall(MatDestroy(&A));
174: PetscCall(MatDestroy(&B));
175: PetscCall(FNDestroy(&f1));
176: PetscCall(FNDestroy(&f2));
177: PetscCall(FNDestroy(&f3));
178: PetscCall(PetscFree(ctx));
179: PetscCall(SlepcFinalize());
180: return 0;
181: }
183: /*
184: Function for user-defined stopping test.
186: Ignores the value of nev. It only takes into account the number of
187: eigenpairs that have converged in recent outer iterations (restarts);
188: if no new eigenvalues have converged in the last few restarts,
189: we stop the iteration, assuming that no more eigenvalues are present
190: inside the region.
191: */
192: PetscErrorCode MyStoppingTest(NEP nep,PetscInt its,PetscInt max_it,PetscInt nconv,PetscInt nev,NEPConvergedReason *reason,void *ptr)
193: {
194: CTX_DELAY *ctx = (CTX_DELAY*)ptr;
196: PetscFunctionBeginUser;
197: /* check usual termination conditions, but ignoring the case nconv>=nev */
198: PetscCall(NEPStoppingBasic(nep,its,max_it,nconv,PETSC_MAX_INT,reason,NULL));
199: if (*reason==NEP_CONVERGED_ITERATING) {
200: /* check if nconv is the same as before */
201: if (nconv==ctx->lastnconv) ctx->nreps++;
202: else {
203: ctx->lastnconv = nconv;
204: ctx->nreps = 0;
205: }
206: /* check if no eigenvalues converged in last 10 restarts */
207: if (nconv && ctx->nreps>10) *reason = NEP_CONVERGED_USER;
208: }
209: PetscFunctionReturn(PETSC_SUCCESS);
210: }
212: /*TEST
214: test:
215: suffix: 1
216: args: -terse
218: TEST*/