Actual source code: ex12.c
1: /*$Id: ex12.c,v 1.41 2001/08/07 21:31:49 bsmith Exp $*/
3: /*
4: Simple example to show how PETSc programs can be run from Matlab.
5: See ex12.m.
6: */
8: static char help[] = "Solves the one dimensional heat equation.nn";
10: #include petscda.h
11: #include petscsys.h
13: int main(int argc,char **argv)
14: {
15: int rank,size,M = 14,ierr,time_steps = 20,w=1,s=1;
16: DA da;
17: PetscViewer viewer;
18: Vec local,global,copy;
19: PetscScalar *localptr,*copyptr;
20: PetscReal h,k;
21: int localsize,j,i,mybase,myend;
22:
23: PetscInitialize(&argc,&argv,(char*)0,help);
25: PetscOptionsGetInt(PETSC_NULL,"-M",&M,PETSC_NULL);
26: PetscOptionsGetInt(PETSC_NULL,"-time",&time_steps,PETSC_NULL);
27:
28: /* Set up the array */
29: DACreate1d(PETSC_COMM_WORLD,DA_NONPERIODIC,M,w,s,PETSC_NULL,&da);
30: DACreateGlobalVector(da,&global);
31: DACreateLocalVector(da,&local);
32: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
33: MPI_Comm_size(PETSC_COMM_WORLD,&size);
35: /* Make copy of local array for doing updates */
36: VecDuplicate(local,©);
37: VecGetArray (copy,©ptr);
39: /* Set Up Display to Show Heat Graph */
40: viewer = PETSC_VIEWER_SOCKET_WORLD;
42: /* determine starting point of each processor */
43: VecGetOwnershipRange(global,&mybase,&myend);
45: /* Initialize the Array */
46: VecGetLocalSize (local,&localsize);
47: VecGetArray (local,&localptr);
48: localptr[0] = copyptr[0] = 0.0;
49: localptr[localsize-1] = copyptr[localsize-1] = 1.0;
50: for (i=1; i<localsize-1; i++) {
51: j=(i-1)+mybase;
52: localptr[i] = sin((PETSC_PI*j*6)/((PetscReal)M)
53: + 1.2 * sin((PETSC_PI*j*2)/((PetscReal)M))) * 4+4;
54: }
56: VecRestoreArray (copy,©ptr);
57: VecRestoreArray(local,&localptr);
58: DALocalToGlobal(da,local,INSERT_VALUES,global);
60: /* Assign Parameters */
61: h= 1.0/M;
62: k= h*h/2.2;
64: for (j=0; j<time_steps; j++) {
66: /* Global to Local */
67: DAGlobalToLocalBegin(da,global,INSERT_VALUES,local);
68: DAGlobalToLocalEnd(da,global,INSERT_VALUES,local);
70: /*Extract local array */
71: VecGetArray(local,&localptr);
72: VecGetArray (copy,©ptr);
74: /* Update Locally - Make array of new values */
75: /* Note: I don't do anything for the first and last entry */
76: for (i=1; i< localsize-1; i++) {
77: copyptr[i] = localptr[i] + (k/(h*h)) *
78: (localptr[i+1]-2.0*localptr[i]+localptr[i-1]);
79: }
80:
81: VecRestoreArray (copy,©ptr);
82: VecRestoreArray(local,&localptr);
84: /* Local to Global */
85: DALocalToGlobal(da,copy,INSERT_VALUES,global);
86:
87: /* View Wave */
88: VecView(global,viewer);
90: }
92: VecDestroy(copy);
93: VecDestroy(local);
94: VecDestroy(global);
95: DADestroy(da);
96: PetscFinalize();
97: return 0;
98: }
99: