In current SymPy, derivative such as dx/d(x+1) is not allowed. Instead, one might use `Derivative(f(x)-1, f(x)).subs(f(x), x+1)`. Although this is mathematically rigorous, the former expression is sometimes used as well, at least in the field of engineering.
Hence I carefully suggest; how about introducing a `rigorous` parameter to `Derivative`? When `rigorous=True`, which is a default value, `Derivative` behaves as it does now. It does not allow dx/d(x+1). When `rigorous=False`, user can have dx/d(x+1) and also evaluate it to 1. Similary, dx/df(x) = 1/(df(x)/dx) is allowed if `rigorous=False`. User must be aware that this may lead to mathematically incorrect result, and use this feature at own risk. -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/8f1de3aa-3d1e-4647-aef4-03ff2720d8fc%40googlegroups.com.
