computing with formulas natural question to ask is why we need three different ways to import module why not use the simple from math import and gain access to all the mathematics functions we needthe reason is that we will often import from several modules in the same programand some of these modules can contain functions with identical names in these cases it is useful to have some control over which functions are actually usedeither by selecting only what we need from each moduleas in from math import sqrtor by importing with import math so that all the functions must be prefixed with the module name to avoid confusion laterit might be good to get into the habit of importing modules in this manner right awayalthoughin small programs where we import only single modulethere is nothing wrong with from math import as another example of computing with functions from mathconsider evaluating the bell-shaped gaussian function  - exp ( ps for and for this calculationwe need to import the square rootthe exponential functionand from the math moduleand the python code may look as followsfrom math import sqrtpiexp /(sqrt( *pi)*sexp(- *(( - )/ )** print(fnotice that for this more complex formula it is very easy to make mistakes with the parentheses such errors will often lead to an error message that points to syntax error on the next line of your program this can be confusing at firstso it is useful to be aware of if you obtain an error message pointing to line directly below complex mathematical formulathe source is usually missing closing parenthesis in the formula itself finding information about python modules at this pointit is natural to ask how we know where to find the functions we want say we need to compute with complex numbers how can we know if there is module in python for thisandif sowhat is it calledgenerallylearning about the useful modules and what they contain are part of learning python programmingbut knowing where to find such information could be even more important an excellent source is the python library reference (the standard modules that are distributed with python more generallya google search for complex numbers python quickly leads us to the cmath modulewhich contains mostly the same functions as mathbut with support for complex numbers if we know the name of module and want to check its