[petsc-users] Getting DMDA local coordinates

[Åsmund Ervik]

Dear all,

I'm using a DMDA to manage my grid, and I want to have uniform
coordinates, so I use DMDASetUniformCoordinates. Since I let PETSc
decide the grid partitioning, I need to get the local coordinates, i.e.
xmin,xmax for the local grid. I found the function
DMGetCoordinatesLocal, but I can't seem to figure out how it works (not
in the manual, examples are confusing). What I do is

  call DMDASetUniformCoordinates(SolScal,0.1,1.0,0.0,1.2,0.0,1.0,ierr)
  call DMGetCoordinatesLocal(SolScal,coordVec,ierr)
  call DMDAVecGetArrayF90(SolScal,coordVec,coords,ierr)

Then I have the "coords" F90 array, which has the same dimensions as my
local part of the DA, i.e. dof:imax:jmax:kmax (all starting at 0). Where
in this array can I find the values xmin,xmax etc? It looks really
strange, e.g. a slice in i-direction gives
 0.10
 0.00
 1.20
 0.55
 0.00

I do realize I can compute these on my own, but I think using
DMGetCoordinatesLocal has less potential for errors.

Best regards,
Åsmund Ervik