I am currently working on updating some legacy code that calls the IMSL function DRNNOA. I would like to know if there is a structured way of going about finding functions in the Intel MKL offering that produces the same output as these IMSL functions.
Tangentially, is a structured way of going about finding high quality free implementations of these subroutines online?
You could take a look at the NIST Guide to Available Mathematical Software (GAMS): http://gams.nist.gov/
There is a good search tool there to find the numerical routines you might be looking for. I've used several routines from that site.