emit and radiosity script

I want write a python script to generate a
Photometric Solid, like this, where each face have
a particular emit value.
http://www.comune.firenze.it/servizi_pubblici/scuola/iti-net/artlux/uia/img/fig5-2.gif

To make this, I try tounderstand what’s the phisical meant of emit
parameter.
I’m study hard the radiometry and photometry, and
now I know the balance equation and the emicube
form factor…

I take a look to Blender source, to see the implementation
of radiosity, but I don’t know C very well (I use only python ),
and I’ve a great difficult (**, ->, *, etc…) .

Can you help me? What happen to emit parameter in the
radiosity implementation? Can you describe me the math
use of this value in the radiosity estimation?

Please, help…

Manuel