Actual source code: test3.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[] = "Test the SLP solver with a user-provided EPS.\n\n"
12: "This is a simplified version of ex20.\n"
13: "The command line options are:\n"
14: " -n <n>, where <n> = number of grid subdivisions.\n";
16: /*
17: Solve 1-D PDE
18: -u'' = lambda*u
19: on [0,1] subject to
20: u(0)=0, u'(1)=u(1)*lambda*kappa/(kappa-lambda)
21: */
23: #include <slepcnep.h>
25: /*
26: User-defined routines
27: */
28: PetscErrorCode FormFunction(NEP,PetscScalar,Mat,Mat,void*);
29: PetscErrorCode FormJacobian(NEP,PetscScalar,Mat,void*);
31: /*
32: User-defined application context
33: */
34: typedef struct {
35: PetscScalar kappa; /* ratio between stiffness of spring and attached mass */
36: PetscReal h; /* mesh spacing */
37: } ApplicationCtx;
39: int main(int argc,char **argv)
40: {
41: NEP nep;
42: EPS eps;
43: KSP ksp;
44: PC pc;
45: Mat F,J;
46: ApplicationCtx ctx;
47: PetscInt n=128;
48: PetscReal deftol;
49: PetscBool terse,flag,ts;
51: PetscFunctionBeginUser;
52: PetscCall(SlepcInitialize(&argc,&argv,(char*)0,help));
53: PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
54: PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\n1-D Nonlinear Eigenproblem, n=%" PetscInt_FMT "\n\n",n));
55: ctx.h = 1.0/(PetscReal)n;
56: ctx.kappa = 1.0;
58: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
59: Create a standalone EPS with appropriate settings
60: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
62: PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));
63: PetscCall(EPSSetType(eps,EPSGD));
64: PetscCall(EPSSetFromOptions(eps));
66: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
67: Create a standalone KSP with appropriate settings
68: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
70: PetscCall(KSPCreate(PETSC_COMM_WORLD,&ksp));
71: PetscCall(KSPSetType(ksp,KSPBCGS));
72: PetscCall(KSPGetPC(ksp,&pc));
73: PetscCall(PCSetType(pc,PCBJACOBI));
74: PetscCall(KSPSetFromOptions(ksp));
76: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
77: Prepare nonlinear eigensolver context
78: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
80: PetscCall(NEPCreate(PETSC_COMM_WORLD,&nep));
82: /* Create Function and Jacobian matrices; set evaluation routines */
83: PetscCall(MatCreate(PETSC_COMM_WORLD,&F));
84: PetscCall(MatSetSizes(F,PETSC_DECIDE,PETSC_DECIDE,n,n));
85: PetscCall(MatSetFromOptions(F));
86: PetscCall(MatSeqAIJSetPreallocation(F,3,NULL));
87: PetscCall(MatMPIAIJSetPreallocation(F,3,NULL,1,NULL));
88: PetscCall(NEPSetFunction(nep,F,F,FormFunction,&ctx));
90: PetscCall(MatCreate(PETSC_COMM_WORLD,&J));
91: PetscCall(MatSetSizes(J,PETSC_DECIDE,PETSC_DECIDE,n,n));
92: PetscCall(MatSetFromOptions(J));
93: PetscCall(MatSeqAIJSetPreallocation(J,3,NULL));
94: PetscCall(MatMPIAIJSetPreallocation(F,3,NULL,1,NULL));
95: PetscCall(NEPSetJacobian(nep,J,FormJacobian,&ctx));
97: /* Set options */
98: PetscCall(NEPSetType(nep,NEPSLP));
99: PetscCall(NEPSLPSetEPS(nep,eps));
100: PetscCall(NEPSLPSetKSP(nep,ksp));
101: PetscCall(NEPSetFromOptions(nep));
103: /* Print some options */
104: PetscCall(PetscObjectTypeCompare((PetscObject)nep,NEPSLP,&flag));
105: if (flag) {
106: PetscCall(NEPGetTwoSided(nep,&ts));
107: if (ts) {
108: PetscCall(NEPSLPGetDeflationThreshold(nep,&deftol));
109: PetscCall(PetscPrintf(PETSC_COMM_WORLD," Two-sided solve with deflation threshold=%g\n",(double)deftol));
110: }
111: }
113: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
114: Solve the eigensystem
115: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
117: PetscCall(NEPSolve(nep));
119: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
120: Display solution and clean up
121: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
123: /* show detailed info unless -terse option is given by user */
124: PetscCall(PetscOptionsHasName(NULL,NULL,"-terse",&terse));
125: if (terse) PetscCall(NEPErrorView(nep,NEP_ERROR_RELATIVE,NULL));
126: else {
127: PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL));
128: PetscCall(NEPConvergedReasonView(nep,PETSC_VIEWER_STDOUT_WORLD));
129: PetscCall(NEPErrorView(nep,NEP_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD));
130: PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
131: }
133: PetscCall(NEPDestroy(&nep));
134: PetscCall(EPSDestroy(&eps));
135: PetscCall(KSPDestroy(&ksp));
136: PetscCall(MatDestroy(&F));
137: PetscCall(MatDestroy(&J));
138: PetscCall(SlepcFinalize());
139: return 0;
140: }
142: /* ------------------------------------------------------------------- */
143: /*
144: FormFunction - Computes Function matrix T(lambda)
146: Input Parameters:
147: . nep - the NEP context
148: . lambda - the scalar argument
149: . ctx - optional user-defined context, as set by NEPSetFunction()
151: Output Parameters:
152: . fun - Function matrix
153: . B - optionally different preconditioning matrix
154: */
155: PetscErrorCode FormFunction(NEP nep,PetscScalar lambda,Mat fun,Mat B,void *ctx)
156: {
157: ApplicationCtx *user = (ApplicationCtx*)ctx;
158: PetscScalar A[3],c,d;
159: PetscReal h;
160: PetscInt i,n,j[3],Istart,Iend;
161: PetscBool FirstBlock=PETSC_FALSE,LastBlock=PETSC_FALSE;
163: PetscFunctionBeginUser;
164: /*
165: Compute Function entries and insert into matrix
166: */
167: PetscCall(MatGetSize(fun,&n,NULL));
168: PetscCall(MatGetOwnershipRange(fun,&Istart,&Iend));
169: if (Istart==0) FirstBlock=PETSC_TRUE;
170: if (Iend==n) LastBlock=PETSC_TRUE;
171: h = user->h;
172: c = user->kappa/(lambda-user->kappa);
173: d = n;
175: /*
176: Interior grid points
177: */
178: for (i=(FirstBlock? Istart+1: Istart);i<(LastBlock? Iend-1: Iend);i++) {
179: j[0] = i-1; j[1] = i; j[2] = i+1;
180: A[0] = A[2] = -d-lambda*h/6.0; A[1] = 2.0*(d-lambda*h/3.0);
181: PetscCall(MatSetValues(fun,1,&i,3,j,A,INSERT_VALUES));
182: }
184: /*
185: Boundary points
186: */
187: if (FirstBlock) {
188: i = 0;
189: j[0] = 0; j[1] = 1;
190: A[0] = 2.0*(d-lambda*h/3.0); A[1] = -d-lambda*h/6.0;
191: PetscCall(MatSetValues(fun,1,&i,2,j,A,INSERT_VALUES));
192: }
194: if (LastBlock) {
195: i = n-1;
196: j[0] = n-2; j[1] = n-1;
197: A[0] = -d-lambda*h/6.0; A[1] = d-lambda*h/3.0+lambda*c;
198: PetscCall(MatSetValues(fun,1,&i,2,j,A,INSERT_VALUES));
199: }
201: /*
202: Assemble matrix
203: */
204: PetscCall(MatAssemblyBegin(B,MAT_FINAL_ASSEMBLY));
205: PetscCall(MatAssemblyEnd(B,MAT_FINAL_ASSEMBLY));
206: if (fun != B) {
207: PetscCall(MatAssemblyBegin(fun,MAT_FINAL_ASSEMBLY));
208: PetscCall(MatAssemblyEnd(fun,MAT_FINAL_ASSEMBLY));
209: }
210: PetscFunctionReturn(PETSC_SUCCESS);
211: }
213: /* ------------------------------------------------------------------- */
214: /*
215: FormJacobian - Computes Jacobian matrix T'(lambda)
217: Input Parameters:
218: . nep - the NEP context
219: . lambda - the scalar argument
220: . ctx - optional user-defined context, as set by NEPSetJacobian()
222: Output Parameters:
223: . jac - Jacobian matrix
224: . B - optionally different preconditioning matrix
225: */
226: PetscErrorCode FormJacobian(NEP nep,PetscScalar lambda,Mat jac,void *ctx)
227: {
228: ApplicationCtx *user = (ApplicationCtx*)ctx;
229: PetscScalar A[3],c;
230: PetscReal h;
231: PetscInt i,n,j[3],Istart,Iend;
232: PetscBool FirstBlock=PETSC_FALSE,LastBlock=PETSC_FALSE;
234: PetscFunctionBeginUser;
235: /*
236: Compute Jacobian entries and insert into matrix
237: */
238: PetscCall(MatGetSize(jac,&n,NULL));
239: PetscCall(MatGetOwnershipRange(jac,&Istart,&Iend));
240: if (Istart==0) FirstBlock=PETSC_TRUE;
241: if (Iend==n) LastBlock=PETSC_TRUE;
242: h = user->h;
243: c = user->kappa/(lambda-user->kappa);
245: /*
246: Interior grid points
247: */
248: for (i=(FirstBlock? Istart+1: Istart);i<(LastBlock? Iend-1: Iend);i++) {
249: j[0] = i-1; j[1] = i; j[2] = i+1;
250: A[0] = A[2] = -h/6.0; A[1] = -2.0*h/3.0;
251: PetscCall(MatSetValues(jac,1,&i,3,j,A,INSERT_VALUES));
252: }
254: /*
255: Boundary points
256: */
257: if (FirstBlock) {
258: i = 0;
259: j[0] = 0; j[1] = 1;
260: A[0] = -2.0*h/3.0; A[1] = -h/6.0;
261: PetscCall(MatSetValues(jac,1,&i,2,j,A,INSERT_VALUES));
262: }
264: if (LastBlock) {
265: i = n-1;
266: j[0] = n-2; j[1] = n-1;
267: A[0] = -h/6.0; A[1] = -h/3.0-c*c;
268: PetscCall(MatSetValues(jac,1,&i,2,j,A,INSERT_VALUES));
269: }
271: /*
272: Assemble matrix
273: */
274: PetscCall(MatAssemblyBegin(jac,MAT_FINAL_ASSEMBLY));
275: PetscCall(MatAssemblyEnd(jac,MAT_FINAL_ASSEMBLY));
276: PetscFunctionReturn(PETSC_SUCCESS);
277: }
279: /*TEST
281: test:
282: args: -nep_target 21 -terse
283: requires: !single
284: test:
285: suffix: 1
286: test:
287: suffix: 1_ts
288: args: -nep_two_sided
290: TEST*/