[Paraview] A function under XDMF file

[Pierre Maruzewski]

Hi Everyone,

I need an example of how to write a function under XDMF file. This 
function will manage variables from a hdf5 file.
For example, I stored two arrays in h5: A and B.
I want thanks to a formula or function under xdmf an additional 
variables C = A+B.

Thanks a lot.

Pierre