Actual source code: ex3.c


  2: static char help[] = "Tests relaxation for dense matrices.\n\n";

  4: #include <petscmat.h>

  6: int main(int argc, char **args)
  7: {
  8:   Mat         C;
  9:   Vec         u, x, b, e;
 10:   PetscInt    i, n = 10, midx[3];
 11:   PetscScalar v[3];
 12:   PetscReal   omega = 1.0, norm;

 15:   PetscInitialize(&argc, &args, (char *)0, help);
 16:   PetscOptionsGetReal(NULL, NULL, "-omega", &omega, NULL);
 17:   PetscOptionsGetInt(NULL, NULL, "-n", &n, NULL);

 19:   MatCreate(PETSC_COMM_SELF, &C);
 20:   MatSetSizes(C, n, n, n, n);
 21:   MatSetType(C, MATSEQDENSE);
 22:   MatSetUp(C);
 23:   VecCreateSeq(PETSC_COMM_SELF, n, &b);
 24:   VecCreateSeq(PETSC_COMM_SELF, n, &x);
 25:   VecCreateSeq(PETSC_COMM_SELF, n, &u);
 26:   VecCreateSeq(PETSC_COMM_SELF, n, &e);
 27:   VecSet(u, 1.0);
 28:   VecSet(x, 0.0);

 30:   v[0] = -1.;
 31:   v[1] = 2.;
 32:   v[2] = -1.;
 33:   for (i = 1; i < n - 1; i++) {
 34:     midx[0] = i - 1;
 35:     midx[1] = i;
 36:     midx[2] = i + 1;
 37:     MatSetValues(C, 1, &i, 3, midx, v, INSERT_VALUES);
 38:   }
 39:   i       = 0;
 40:   midx[0] = 0;
 41:   midx[1] = 1;
 42:   v[0]    = 2.0;
 43:   v[1]    = -1.;
 44:   MatSetValues(C, 1, &i, 2, midx, v, INSERT_VALUES);
 45:   i       = n - 1;
 46:   midx[0] = n - 2;
 47:   midx[1] = n - 1;
 48:   v[0]    = -1.0;
 49:   v[1]    = 2.;
 50:   MatSetValues(C, 1, &i, 2, midx, v, INSERT_VALUES);

 52:   MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY);
 53:   MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY);

 55:   MatMult(C, u, b);

 57:   for (i = 0; i < n; i++) {
 58:     MatSOR(C, b, omega, SOR_FORWARD_SWEEP, 0.0, 1, 1, x);
 59:     VecWAXPY(e, -1.0, x, u);
 60:     VecNorm(e, NORM_2, &norm);
 61:     PetscPrintf(PETSC_COMM_SELF, "2-norm of error %g\n", (double)norm);
 62:   }
 63:   MatDestroy(&C);
 64:   VecDestroy(&x);
 65:   VecDestroy(&b);
 66:   VecDestroy(&u);
 67:   VecDestroy(&e);
 68:   PetscFinalize();
 69:   return 0;
 70: }

 72: /*TEST

 74:    test:

 76: TEST*/