# help

Christophe Geuzaine Christophe.Geuzaine at ulg.ac.be
Fri May 25 21:09:59 CEST 2001

```Lin Ji wrote:
>
> Hi, Christophe,
>     We talked to Jean-Francois about the multiple wave fronts thing. It turns
> out we misinterpreted the result shown by gmsh. What we saw are the contour
> level sets of the wave. When Jean-Francois showed us the wave in 3-D, it is
> exactly what we expected. It is pretty nice. I like it.
>     Now there is one step away for us to use the data computed by 'getdp' in
> our project. That is to export the data to the format we want. Is there an
> available format that stores the solution in a 3-D array, say U where
> U(i,j,k) is the value of the solution at t(i), y(j), x(k) and t(i) = i*dt,
> (y(j), x(k)) is the node of a uniform rectangular meshing, i.e. y(j) = ymin +
> j*dy, x(k) = xmin + k*dx?  Thanks.
>

You may use the 'TimeTable' format together with the 'OnPlane'
directive (which interpolates the solution on a grid specified by three
points + the number of samples along the two axes), i.e.

Print[ u ,
OnPlane { {xmin,ymin,0} {xmax,ymin,0} {xmin,ymax,0} } {nbx,nby} ,
Format TimeTable,
File "out" ] ;

A typical line in the file "out" will be 'timestep time x y z value'.

You may also use the 'Table' format (the difference is that this format
is 'space' oriented). A line will look like '15 num  x y 0  0 0 1
values', where 'num' is the number of the finite element to which the
point (x,y) belongs, and 'values' is the list of solutions for all time
steps at the point (x,y). So what you want is now located in columns 3
(x-coordinate), 4 (y-coordinate) and 9, 10, 11, 12, ... (the values).
The time is not stored in this format.

My best,

Christophe

--
Christophe Geuzaine

Tel: 32 (0) 4 366 37 10    http://geuz.org
Fax: 32 (0) 4 366 29 10    mailto:Christophe.Geuzaine at ulg.ac.be
```