Actual source code: test4.c
slepc-3.11.2 2019-07-30
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 the RII solver with a user-provided KSP.\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: KSP ksp;
43: PC pc;
44: Mat F,J;
45: ApplicationCtx ctx;
46: PetscInt n=128,lag,its;
47: PetscBool terse,flg,cct;
50: SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
51: PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
52: PetscPrintf(PETSC_COMM_WORLD,"\n1-D Nonlinear Eigenproblem, n=%D\n\n",n);
53: ctx.h = 1.0/(PetscReal)n;
54: ctx.kappa = 1.0;
56: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
57: Create a standalone KSP with appropriate settings
58: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
60: KSPCreate(PETSC_COMM_WORLD,&ksp);
61: KSPSetType(ksp,KSPBCGS);
62: KSPGetPC(ksp,&pc);
63: PCSetType(pc,PCBJACOBI);
64: KSPSetFromOptions(ksp);
66: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
67: Prepare nonlinear eigensolver context
68: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
70: NEPCreate(PETSC_COMM_WORLD,&nep);
72: /* Create Function and Jacobian matrices; set evaluation routines */
73: MatCreate(PETSC_COMM_WORLD,&F);
74: MatSetSizes(F,PETSC_DECIDE,PETSC_DECIDE,n,n);
75: MatSetFromOptions(F);
76: MatSeqAIJSetPreallocation(F,3,NULL);
77: MatMPIAIJSetPreallocation(F,3,NULL,1,NULL);
78: MatSetUp(F);
79: NEPSetFunction(nep,F,F,FormFunction,&ctx);
81: MatCreate(PETSC_COMM_WORLD,&J);
82: MatSetSizes(J,PETSC_DECIDE,PETSC_DECIDE,n,n);
83: MatSetFromOptions(J);
84: MatSeqAIJSetPreallocation(J,3,NULL);
85: MatMPIAIJSetPreallocation(F,3,NULL,1,NULL);
86: MatSetUp(J);
87: NEPSetJacobian(nep,J,FormJacobian,&ctx);
89: NEPSetType(nep,NEPRII);
90: NEPRIISetKSP(nep,ksp);
91: NEPRIISetMaximumIterations(nep,6);
92: NEPRIISetConstCorrectionTol(nep,PETSC_TRUE);
93: NEPSetFromOptions(nep);
95: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
96: Solve the eigensystem
97: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
99: NEPSolve(nep);
100: PetscObjectTypeCompare((PetscObject)nep,NEPRII,&flg);
101: if (flg) {
102: NEPRIIGetMaximumIterations(nep,&its);
103: NEPRIIGetLagPreconditioner(nep,&lag);
104: NEPRIIGetConstCorrectionTol(nep,&cct);
105: PetscPrintf(PETSC_COMM_WORLD," Maximum inner iterations of RII is %D\n",its);
106: PetscPrintf(PETSC_COMM_WORLD," Preconditioner rebuilt every %D iterations\n",lag);
107: if (cct) { PetscPrintf(PETSC_COMM_WORLD," Using a constant correction tolerance\n"); }
108: PetscPrintf(PETSC_COMM_WORLD,"\n");
109: }
111: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
112: Display solution and clean up
113: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
115: /* show detailed info unless -terse option is given by user */
116: PetscOptionsHasName(NULL,NULL,"-terse",&terse);
117: if (terse) {
118: NEPErrorView(nep,NEP_ERROR_RELATIVE,NULL);
119: } else {
120: PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
121: NEPReasonView(nep,PETSC_VIEWER_STDOUT_WORLD);
122: NEPErrorView(nep,NEP_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
123: PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
124: }
126: NEPDestroy(&nep);
127: KSPDestroy(&ksp);
128: MatDestroy(&F);
129: MatDestroy(&J);
130: SlepcFinalize();
131: return ierr;
132: }
134: /* ------------------------------------------------------------------- */
135: /*
136: FormFunction - Computes Function matrix T(lambda)
138: Input Parameters:
139: . nep - the NEP context
140: . lambda - the scalar argument
141: . ctx - optional user-defined context, as set by NEPSetFunction()
143: Output Parameters:
144: . fun - Function matrix
145: . B - optionally different preconditioning matrix
146: */
147: PetscErrorCode FormFunction(NEP nep,PetscScalar lambda,Mat fun,Mat B,void *ctx)
148: {
150: ApplicationCtx *user = (ApplicationCtx*)ctx;
151: PetscScalar A[3],c,d;
152: PetscReal h;
153: PetscInt i,n,j[3],Istart,Iend;
154: PetscBool FirstBlock=PETSC_FALSE,LastBlock=PETSC_FALSE;
157: /*
158: Compute Function entries and insert into matrix
159: */
160: MatGetSize(fun,&n,NULL);
161: MatGetOwnershipRange(fun,&Istart,&Iend);
162: if (Istart==0) FirstBlock=PETSC_TRUE;
163: if (Iend==n) LastBlock=PETSC_TRUE;
164: h = user->h;
165: c = user->kappa/(lambda-user->kappa);
166: d = n;
168: /*
169: Interior grid points
170: */
171: for (i=(FirstBlock? Istart+1: Istart);i<(LastBlock? Iend-1: Iend);i++) {
172: j[0] = i-1; j[1] = i; j[2] = i+1;
173: A[0] = A[2] = -d-lambda*h/6.0; A[1] = 2.0*(d-lambda*h/3.0);
174: MatSetValues(fun,1,&i,3,j,A,INSERT_VALUES);
175: }
177: /*
178: Boundary points
179: */
180: if (FirstBlock) {
181: i = 0;
182: j[0] = 0; j[1] = 1;
183: A[0] = 2.0*(d-lambda*h/3.0); A[1] = -d-lambda*h/6.0;
184: MatSetValues(fun,1,&i,2,j,A,INSERT_VALUES);
185: }
187: if (LastBlock) {
188: i = n-1;
189: j[0] = n-2; j[1] = n-1;
190: A[0] = -d-lambda*h/6.0; A[1] = d-lambda*h/3.0+lambda*c;
191: MatSetValues(fun,1,&i,2,j,A,INSERT_VALUES);
192: }
194: /*
195: Assemble matrix
196: */
197: MatAssemblyBegin(B,MAT_FINAL_ASSEMBLY);
198: MatAssemblyEnd(B,MAT_FINAL_ASSEMBLY);
199: if (fun != B) {
200: MatAssemblyBegin(fun,MAT_FINAL_ASSEMBLY);
201: MatAssemblyEnd(fun,MAT_FINAL_ASSEMBLY);
202: }
203: return(0);
204: }
206: /* ------------------------------------------------------------------- */
207: /*
208: FormJacobian - Computes Jacobian matrix T'(lambda)
210: Input Parameters:
211: . nep - the NEP context
212: . lambda - the scalar argument
213: . ctx - optional user-defined context, as set by NEPSetJacobian()
215: Output Parameters:
216: . jac - Jacobian matrix
217: . B - optionally different preconditioning matrix
218: */
219: PetscErrorCode FormJacobian(NEP nep,PetscScalar lambda,Mat jac,void *ctx)
220: {
222: ApplicationCtx *user = (ApplicationCtx*)ctx;
223: PetscScalar A[3],c;
224: PetscReal h;
225: PetscInt i,n,j[3],Istart,Iend;
226: PetscBool FirstBlock=PETSC_FALSE,LastBlock=PETSC_FALSE;
229: /*
230: Compute Jacobian entries and insert into matrix
231: */
232: MatGetSize(jac,&n,NULL);
233: MatGetOwnershipRange(jac,&Istart,&Iend);
234: if (Istart==0) FirstBlock=PETSC_TRUE;
235: if (Iend==n) LastBlock=PETSC_TRUE;
236: h = user->h;
237: c = user->kappa/(lambda-user->kappa);
239: /*
240: Interior grid points
241: */
242: for (i=(FirstBlock? Istart+1: Istart);i<(LastBlock? Iend-1: Iend);i++) {
243: j[0] = i-1; j[1] = i; j[2] = i+1;
244: A[0] = A[2] = -h/6.0; A[1] = -2.0*h/3.0;
245: MatSetValues(jac,1,&i,3,j,A,INSERT_VALUES);
246: }
248: /*
249: Boundary points
250: */
251: if (FirstBlock) {
252: i = 0;
253: j[0] = 0; j[1] = 1;
254: A[0] = -2.0*h/3.0; A[1] = -h/6.0;
255: MatSetValues(jac,1,&i,2,j,A,INSERT_VALUES);
256: }
258: if (LastBlock) {
259: i = n-1;
260: j[0] = n-2; j[1] = n-1;
261: A[0] = -h/6.0; A[1] = -h/3.0-c*c;
262: MatSetValues(jac,1,&i,2,j,A,INSERT_VALUES);
263: }
265: /*
266: Assemble matrix
267: */
268: MatAssemblyBegin(jac,MAT_FINAL_ASSEMBLY);
269: MatAssemblyEnd(jac,MAT_FINAL_ASSEMBLY);
270: return(0);
271: }
273: /*TEST
275: test:
276: suffix: 1
277: args: -nep_target 21 -nep_rii_lag_preconditioner 2 -terse
278: requires: !single
280: TEST*/