Is there a way to show how Mathematica defines a function, such as
In: Something[Sqrt], Out: Sqrt[x] -> x^(1/2)
As far as I understand it the command Definition should do the job, but unfortunately it does not work on built in functions. I am asking because more complicated functions than Sqrt, such as for example the JacobiAmplitude, are not well documented in the Help section, and give different results with different programs.
Since I got a solution containing those functions which are not defined uniformly everywhere, I would need to know how to interpret the output generally so I could do the calculation with pencil and on paper if I had to .
I tried to reconstruct the definitions myself with the informations given at NIST, and I got this far:
That gives the same results like the built in functions for some ranges, but not for others; also it takes literally hours to compute the definitions I defined myself, even when I let the sum run to a small finite value instead of infinity.
The built in JacobiAmplitude in contrast evaluates in a few seconds and for all given input values, so I assume I'm doing something wrong with my own definitions.