[Tutor] Little problem with math module

[tiger12506]

> my problem is, INSIDE the funcion...the variable erro is correct, but
> when i return it to the test...and the test prints it....comes out 0.0.
> Its disturbing...i didnt found a way of solving this.

err is defined in the function so it thinks it's a local variable. You can 
set it to change only the global variable by putting

global err

as the line right after your function def.