1 2 /* 3 Simple example to show how PETSc programs can be run from MATLAB. 4 See ex12.m. 5 */ 6 7 static char help[] = "Solves the one dimensional heat equation.\n\n"; 8 9 #include <petscdm.h> 10 #include <petscdmda.h> 11 12 int main(int argc,char **argv) 13 { 14 PetscMPIInt rank,size; 15 PetscInt M = 14,time_steps = 20,w=1,s=1,localsize,j,i,mybase,myend,globalsize; 16 DM da; 17 Vec global,local; 18 PetscScalar *globalptr,*localptr; 19 PetscReal h,k; 20 21 CHKERRQ(PetscInitialize(&argc,&argv,(char*)0,help)); 22 CHKERRQ(PetscOptionsGetInt(NULL,NULL,"-M",&M,NULL)); 23 CHKERRQ(PetscOptionsGetInt(NULL,NULL,"-time",&time_steps,NULL)); 24 25 /* Set up the array */ 26 CHKERRQ(DMDACreate1d(PETSC_COMM_WORLD,DM_BOUNDARY_NONE,M,w,s,NULL,&da)); 27 CHKERRQ(DMSetFromOptions(da)); 28 CHKERRQ(DMSetUp(da)); 29 CHKERRQ(DMCreateGlobalVector(da,&global)); 30 CHKERRMPI(MPI_Comm_rank(PETSC_COMM_WORLD,&rank)); 31 CHKERRMPI(MPI_Comm_size(PETSC_COMM_WORLD,&size)); 32 33 /* Make copy of local array for doing updates */ 34 CHKERRQ(DMCreateLocalVector(da,&local)); 35 36 /* determine starting point of each processor */ 37 CHKERRQ(VecGetOwnershipRange(global,&mybase,&myend)); 38 39 /* Initialize the Array */ 40 CHKERRQ(VecGetLocalSize (global,&globalsize)); 41 CHKERRQ(VecGetArray (global,&globalptr)); 42 43 for (i=0; i<globalsize; i++) { 44 j = i + mybase; 45 46 globalptr[i] = PetscSinReal((PETSC_PI*j*6)/((PetscReal)M) + 1.2 * PetscSinReal((PETSC_PI*j*2)/((PetscReal)M))) * 4+4; 47 } 48 49 CHKERRQ(VecRestoreArray(global,&localptr)); 50 51 /* Assign Parameters */ 52 h= 1.0/M; 53 k= h*h/2.2; 54 CHKERRQ(VecGetLocalSize(local,&localsize)); 55 56 for (j=0; j<time_steps; j++) { 57 58 /* Global to Local */ 59 CHKERRQ(DMGlobalToLocalBegin(da,global,INSERT_VALUES,local)); 60 CHKERRQ(DMGlobalToLocalEnd(da,global,INSERT_VALUES,local)); 61 62 /*Extract local array */ 63 CHKERRQ(VecGetArray(local,&localptr)); 64 CHKERRQ(VecGetArray (global,&globalptr)); 65 66 /* Update Locally - Make array of new values */ 67 /* Note: I don't do anything for the first and last entry */ 68 for (i=1; i< localsize-1; i++) { 69 globalptr[i-1] = localptr[i] + (k/(h*h)) * (localptr[i+1]-2.0*localptr[i]+localptr[i-1]); 70 } 71 72 CHKERRQ(VecRestoreArray (global,&globalptr)); 73 CHKERRQ(VecRestoreArray(local,&localptr)); 74 75 /* View Wave */ 76 /* Set Up Display to Show Heat Graph */ 77 #if defined(PETSC_USE_SOCKET_VIEWER) 78 CHKERRQ(VecView(global,PETSC_VIEWER_SOCKET_WORLD)); 79 #endif 80 } 81 82 CHKERRQ(VecDestroy(&local)); 83 CHKERRQ(VecDestroy(&global)); 84 CHKERRQ(DMDestroy(&da)); 85 CHKERRQ(PetscFinalize()); 86 return 0; 87 } 88