I need a software to simplify a function $\Phi(x,y)$ which is obtained analytically and is in a much complicated form. I require to rewrite $\Phi(x,y)$ in terms of three other functions $f(x,y)$, $g(x,y)$ and $h(x,y)$. Also, I don't have access to Mathematica.
Is there any software available which can be helpful for the purpose?
https://www.desmos.com/
You can define functions of multiple variables and you can define functions in terms of other functions you have defined.