how to integrate a function of a function in matlab

Here, $Psi$ is a function of y,r and theta. I'm getting error for this triple integration. Any suggestions?

[Rik]

Have a read here (or here for more general advice) and here. It will greatly improve your chances of getting an answer.

[John D'Errico]

What have you tried? That you are getting an error just means you have an error in your code, and we cannot possibly try to guess what your error might be. The crystal ball is always foggy. But it is far easier to show you how to fix your code, than it is to try to write code for you from scratch. That becomes just a doit4me.