how to speed up the symbolic computation?

Hi everyone,

I have written a code using symbolic computation.

In it, first, 20 symbolic variables are defined, after obtaining the symbolic expressions of some intermediate variables containing these variables, the command 'subs' is applied to substitute the 20 symbolic variables in the intermediate variables with numerical ones.

However, this task is quite time-consuming, and that takes quite a long time to finish just part of the results. I also tried to use the matlabFunction to transfer the symbolic intermediate variables into a function, but it still takes quite a long time.

Does anyone can give me some ideas how to speed up the code ?

Thanks so much!