[GRASS-dev] Using GRASS to calculate an index

Greetings All

I’m planning on developing an index to use over RASter images. Is quite an easy expression with a few sums and square roots. All those operations are included in r.mapcalc but instead of doing each operation using image calculation in GUI I want to do an automatic procedure in which I select image A, image B and Image C and he does the rest.

Question: Since those operations are included in r.mapcalc, do I need to do a function or can I just do a Script that is called from the wxPython GUI?

Thanks

Cheerios
Luis Lisboa