[petsc-users] DMDAVecGetArray vs DMDAVecRestoreArray

[Alan Wei]

Dear all,
    I hope you're having a nice day.
    I'm trying to get the x, y-value of a coordinate created by
DMDACreate2d. Lines I wrote down are:

  DMDAGetCoordinateDA(da, &cda);
  DMDAGetGhostedCoordinates(da, &gc);
  DMDAVecGetArray(cda, gc, &coors);

  for (i = xs; i < xs+xm; i++) {
    for (j = ys; j < ys+ym; j++) {
      printf("%f  %f\n", coors[j][i].x, coors[j][i].y);
    }
  }

  DMDAVecRestoreArray(cda, gc, &coors);

I wonder why I need to use "DMDAVecRestoreArray(cda, gc, &coors);" I used it
because the manual said I need. Actually, I tried to comment it out and
there is no difference.

Thanks,
Alan
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