[petsc-users] Creating a 2d geometry by using vector

[Barry Smith]

  Alan,

   I'm not sure what you are getting at but we commonly use tricks like (see 
src/snes/examples/tutorials/ex19.c) 

typedef struct {
  PetscScalar u,v,omega,temp;
} Field;

 Then in this case use a DMDAVecGetArray() to get f and x and then have nice 
notation like

      f[j][i].u     = x[j][i].u;
      f[j][i].v     = x[j][i].v;
      f[j][i].omega = x[j][i].omega - (x[j][i+1].v - x[j][i].v)*dhx; 
      f[j][i].temp  = x[j][i].temp;

note that this means the values are stored interlaced in the vector.

   Barry

On Aug 18, 2011, at 9:03 PM, Alan Wei wrote:

> Dear All,
>     I'm trying to 'draw' a 2-D cylinder in PETSc. It simply restore the x and 
> y coordinate values in two arrays. I wonder if I can use Vec in PETSc to 
> implement it (i.e. defining a vec circle) so that I can call its x or y 
> coordinate by circle.x or circle.y. Is this possible? also, is this a better 
> way than just defining it as two arrays, i.e. x[ ] and y[ ].
> 
> thanks in advance,
> Alan