Actual source code: ex10.c
slepc-3.18.0 2022-10-01
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 shell spectral transformations. "
12: "The problem to be solved is the same as ex1.c and"
13: "corresponds to the Laplacian operator in 1 dimension.\n\n"
14: "The command line options are:\n"
15: " -n <n>, where <n> = number of grid subdivisions = matrix dimension.\n\n";
17: #include <slepceps.h>
19: /* Define context for user-provided spectral transformation */
20: typedef struct {
21: KSP ksp;
22: } SampleShellST;
24: /* Declare routines for user-provided spectral transformation */
25: PetscErrorCode STCreate_User(SampleShellST**);
26: PetscErrorCode STSetUp_User(SampleShellST*,ST);
27: PetscErrorCode STApply_User(ST,Vec,Vec);
28: PetscErrorCode STApplyTranspose_User(ST,Vec,Vec);
29: PetscErrorCode STBackTransform_User(ST,PetscInt,PetscScalar*,PetscScalar*);
30: PetscErrorCode STDestroy_User(SampleShellST*);
32: int main (int argc,char **argv)
33: {
34: Mat A; /* operator matrix */
35: EPS eps; /* eigenproblem solver context */
36: ST st; /* spectral transformation context */
37: SampleShellST *shell; /* user-defined spectral transform context */
38: EPSType type;
39: PetscInt n=30,i,Istart,Iend,nev;
40: PetscBool isShell,terse;
43: SlepcInitialize(&argc,&argv,(char*)0,help);
45: PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
46: PetscPrintf(PETSC_COMM_WORLD,"\n1-D Laplacian Eigenproblem (shell-enabled), n=%" PetscInt_FMT "\n\n",n);
48: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
49: Compute the operator matrix that defines the eigensystem, Ax=kx
50: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
52: MatCreate(PETSC_COMM_WORLD,&A);
53: MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);
54: MatSetFromOptions(A);
55: MatSetUp(A);
57: MatGetOwnershipRange(A,&Istart,&Iend);
58: for (i=Istart;i<Iend;i++) {
59: if (i>0) MatSetValue(A,i,i-1,-1.0,INSERT_VALUES);
60: if (i<n-1) MatSetValue(A,i,i+1,-1.0,INSERT_VALUES);
61: MatSetValue(A,i,i,2.0,INSERT_VALUES);
62: }
63: MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
64: MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
66: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
67: Create the eigensolver and set various options
68: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
70: /*
71: Create eigensolver context
72: */
73: EPSCreate(PETSC_COMM_WORLD,&eps);
75: /*
76: Set operators. In this case, it is a standard eigenvalue problem
77: */
78: EPSSetOperators(eps,A,NULL);
79: EPSSetProblemType(eps,EPS_HEP);
81: /*
82: Set solver parameters at runtime
83: */
84: EPSSetFromOptions(eps);
86: /*
87: Initialize shell spectral transformation if selected by user
88: */
89: EPSGetST(eps,&st);
90: PetscObjectTypeCompare((PetscObject)st,STSHELL,&isShell);
91: if (isShell) {
92: /* Change sorting criterion since this ST example computes values
93: closest to 0 */
94: EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL);
96: /* (Required) Create a context for the user-defined spectral transform;
97: this context can be defined to contain any application-specific data. */
98: STCreate_User(&shell);
99: STShellSetContext(st,shell);
101: /* (Required) Set the user-defined routine for applying the operator */
102: STShellSetApply(st,STApply_User);
104: /* (Optional) Set the user-defined routine for applying the transposed operator */
105: STShellSetApplyTranspose(st,STApplyTranspose_User);
107: /* (Optional) Set the user-defined routine for back-transformation */
108: STShellSetBackTransform(st,STBackTransform_User);
110: /* (Optional) Set a name for the transformation, used for STView() */
111: PetscObjectSetName((PetscObject)st,"MyTransformation");
113: /* (Optional) Do any setup required for the new transformation */
114: STSetUp_User(shell,st);
115: }
117: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
118: Solve the eigensystem
119: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
121: EPSSolve(eps);
123: /*
124: Optional: Get some information from the solver and display it
125: */
126: EPSGetType(eps,&type);
127: PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type);
128: EPSGetDimensions(eps,&nev,NULL,NULL);
129: PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %" PetscInt_FMT "\n",nev);
131: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
132: Display solution and clean up
133: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
135: /* show detailed info unless -terse option is given by user */
136: PetscOptionsHasName(NULL,NULL,"-terse",&terse);
137: if (terse) EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
138: else {
139: PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
140: EPSConvergedReasonView(eps,PETSC_VIEWER_STDOUT_WORLD);
141: EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
142: PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
143: }
144: if (isShell) STDestroy_User(shell);
145: EPSDestroy(&eps);
146: MatDestroy(&A);
147: SlepcFinalize();
148: return 0;
149: }
151: /***********************************************************************/
152: /* Routines for a user-defined shell spectral transformation */
153: /***********************************************************************/
155: /*
156: STCreate_User - This routine creates a user-defined
157: spectral transformation context.
159: Output Parameter:
160: . shell - user-defined spectral transformation context
161: */
162: PetscErrorCode STCreate_User(SampleShellST **shell)
163: {
164: SampleShellST *newctx;
167: PetscNew(&newctx);
168: KSPCreate(PETSC_COMM_WORLD,&newctx->ksp);
169: KSPAppendOptionsPrefix(newctx->ksp,"st_");
170: *shell = newctx;
171: return 0;
172: }
173: /* ------------------------------------------------------------------- */
174: /*
175: STSetUp_User - This routine sets up a user-defined
176: spectral transformation context.
178: Input Parameters:
179: + shell - user-defined spectral transformation context
180: - st - spectral transformation context containing the operator matrices
182: Output Parameter:
183: . shell - fully set up user-defined transformation context
185: Notes:
186: In this example, the user-defined transformation is simply OP=A^-1.
187: Therefore, the eigenpairs converge in reversed order. The KSP object
188: used for the solution of linear systems with A is handled via the
189: user-defined context SampleShellST.
190: */
191: PetscErrorCode STSetUp_User(SampleShellST *shell,ST st)
192: {
193: Mat A;
196: STGetMatrix(st,0,&A);
197: KSPSetOperators(shell->ksp,A,A);
198: KSPSetFromOptions(shell->ksp);
199: return 0;
200: }
201: /* ------------------------------------------------------------------- */
202: /*
203: STApply_User - This routine demonstrates the use of a
204: user-provided spectral transformation.
206: Input Parameters:
207: + st - spectral transformation context
208: - x - input vector
210: Output Parameter:
211: . y - output vector
213: Notes:
214: The transformation implemented in this code is just OP=A^-1 and
215: therefore it is of little use, merely as an example of working with
216: a STSHELL.
217: */
218: PetscErrorCode STApply_User(ST st,Vec x,Vec y)
219: {
220: SampleShellST *shell;
223: STShellGetContext(st,&shell);
224: KSPSolve(shell->ksp,x,y);
225: return 0;
226: }
227: /* ------------------------------------------------------------------- */
228: /*
229: STApplyTranspose_User - This is not required unless using a two-sided
230: eigensolver.
232: Input Parameters:
233: + st - spectral transformation context
234: - x - input vector
236: Output Parameter:
237: . y - output vector
238: */
239: PetscErrorCode STApplyTranspose_User(ST st,Vec x,Vec y)
240: {
241: SampleShellST *shell;
244: STShellGetContext(st,&shell);
245: KSPSolveTranspose(shell->ksp,x,y);
246: return 0;
247: }
248: /* ------------------------------------------------------------------- */
249: /*
250: STBackTransform_User - This routine demonstrates the use of a
251: user-provided spectral transformation.
253: Input Parameters:
254: + st - spectral transformation context
255: - n - number of eigenvalues to transform
257: Input/Output Parameters:
258: + eigr - pointer to real part of eigenvalues
259: - eigi - pointer to imaginary part of eigenvalues
261: Notes:
262: This code implements the back transformation of eigenvalues in
263: order to retrieve the eigenvalues of the original problem. In this
264: example, simply set k_i = 1/k_i.
265: */
266: PetscErrorCode STBackTransform_User(ST st,PetscInt n,PetscScalar *eigr,PetscScalar *eigi)
267: {
268: PetscInt j;
271: for (j=0;j<n;j++) {
272: eigr[j] = 1.0 / eigr[j];
273: }
274: return 0;
275: }
276: /* ------------------------------------------------------------------- */
277: /*
278: STDestroy_User - This routine destroys a user-defined
279: spectral transformation context.
281: Input Parameter:
282: . shell - user-defined spectral transformation context
283: */
284: PetscErrorCode STDestroy_User(SampleShellST *shell)
285: {
287: KSPDestroy(&shell->ksp);
288: PetscFree(shell);
289: return 0;
290: }
292: /*TEST
294: testset:
295: args: -eps_nev 5 -eps_non_hermitian -terse
296: output_file: output/ex10_1.out
297: test:
298: suffix: 1_sinvert
299: args: -st_type sinvert
300: test:
301: suffix: 1_sinvert_twoside
302: args: -st_type sinvert -eps_balance twoside
303: requires: !single
304: test:
305: suffix: 1_shell
306: args: -st_type shell
307: requires: !single
308: test:
309: suffix: 1_shell_twoside
310: args: -st_type shell -eps_balance twoside
312: TEST*/