MrParosk:

symbolic methods


No symbolic methods. That would be insane. It uses calculus based on FORTRAN style and GRAPH it creates.
If you have to calculate derivative of a function y = f(a,b,c) at point a, then you will measure y changes with respect to the change of the variable a.
da = (f(a+e,b,c)-f(a,b,c))/e
print(da)

where e is some small number.