How to implement Complex exponential functions in C ???

Hi everyone

I am trying to write a code for an IIR filter. And for that purpose i need to implement the below funtion in C :-

Now, am facing problem ... wel rather i have no idea , as to how to implement the e^jw function. The value of w is known to me and n = the sample number.

It would be great if anyone could help me out.
Thanks a lot !!

 

Post the code you have tried so far, that'll make it easier for people to help you.