C Function Question

Hello,

I have a C function that takes 4 arrays, does some math* to them, and
ends up with an array of floats. I'd like to return this in standard
postgres array form (ala SELECT) to be used in an subselect in an
UPDATE query. Right now, this is all done in perl (which is perfectly
adequate), but just for kicks I'd like to port it to C.

The prob. is I can't seem to find a straightforward way to get from
the array of floats to the postgres select form. I kick in the right
direction would be great!

Thanks,
Bill


* get the average of non-zero values in each array over each
  index. ending up with an array of averages.