UDF for streamfunction
 

Could anybody help me how to write a udf for streamfunction for given u,v data ?

I KNOW that streamfunction contours can be directly viewed from post-processing facility in FLUENT, but my problem is related to development of functions similar to streamfunction from u,v data.
streamfunction is defined as,

u= d / dy, v=- d /dx

A simple udf for streamfunction should help me getting started.

Thanks a lot..!