I need to speed up my code

I have code that works perfectly fine, but is very slow. I need to understand how to speed it up. I've run the profiler and there seems to be an issue with one of my functions that I wrote. This is a prototype code and I will need to change out the function zeta, as it's essentially a constitutive relation, so ideally, I will need to change it for different materials.

What can I do to speed up the code?

[Dyuman Joshi]

From a quick glance over your code -

1> Add comments in your code. It's difficult to understand what you are trying to do without any relevant information.

2> Avoid using global. Pass the variables to the local functions as inputs.