lat = eval(strcat(varin, 'intlat')
lat = eval(strcat(varin, 'intlon')
DO NOT DO THIS.
Your approach is forcing down a very bad path. Using eval and/or magically accessing variables in other workspace is one way that beginners force themselves into writing slow, complex, buggy code that is hard to debug. Read this to know why:
"Is there a solution to this? I've heard of global variable but also that they really aren't recommended."
Global variables should be avoided. Magically accessing variable names should be avoided. The best way to pass data from one function to another is to simply pass it as input/output arguments. This is exactly what the MATLAB documentation recommends:
"I'm trying to write a function to avoid repetition in my code, I and noticed that one task always comes in pairs"
Then you should put your data into one array and used loops and indexing or vectorized code. Indexing is simple, neat, easy to debug, and very efficient. Vectorized code is often simple and efficient. Unlike what you are doing.
