Hi!

I have the following function:

and I want to calculate it for a certain set of r, theta and t, but when I use subs, the theta variable is also subsituted int the integral's parameters and I get the folllowing result:

I really don't understand why it does that given that there is no issue for the r variable...

Thanks in advance for your help!

P-S: please forgive my poor English : I'm a French student...

Florent