Implementing "do this, then return that" in function definitions

Question

In Python, I often use local variables in defining functions, like so:

def f(x):
   k = initialk
   < 'do something to k' >
   return(k)

I would like to do something similar in Mathematica for instance, I would want:

f[x_]:=
For[i=0;k=x,i<x,i++,k=k^2+1];
Return[k]

to return $(\cdots((x^2+1)^2+1)^2+\cdots1)^2$.

How does one ordinarily do this in Mathematica?

Module, With, or Block will do what you're looking for. — Carl Lange, Mar 08 '20 at 18:23
Don’t try to program in Mathematica by reproducing Python practices. You will write inefficient code and end up very frustrated. — MarcoB, Mar 09 '20 at 02:47
@MarcoB Is there a "Good Coding Practices for Mathematica" somewhere that I could refer to? — R. Burton, Mar 09 '20 at 19:25
@R.Burton if you asked that as a question, I think you would get some pointers to suitable material. — mikado, Mar 09 '20 at 21:18
@R.Burton For a start, see Where can I find examples of good Mathematica programming practice? — MarcoB, Mar 09 '20 at 22:16

score 10 · Accepted Answer · answered Mar 08 '20 at 18:25

10

If you want, you could write some thing like this

f[x_] := Module[{k = x},
  Do[k = k^2 + 1, {i, 0, x - 1}];
  k]

A more natural form would be

f[x_] := Nest[#^2 + 1 &, x, x]

answered Mar 08 '20 at 18:25

mikado

1 Answers1