I'd like to define an custom function f(x).
ln(3) + 3if the function is set to
ln(x) + 3.
One should be able change the function:
This should only affect future uses of
And it should be possible to define the first three derivatives..
The commands do not have do be this way. There may be a more elegant/practical way. Warning: It should work in this environment: https://tex.stackexchange.com/a/299720/101053
Edit: Changed derivate to derivative; It's unclear what "define the derivative" should mean. I tried to say that I can simply add other functions (whether derivative or nor).