"from math import sqrt" works but "import math" does not work. What is the reason?

Question

I am pretty new in programming, just learning python.

I'm using Komodo Edit 9.0 to write codes. So, when I write "from math import sqrt", I can use the "sqrt" function without any problem. But if I only write "import math", then "sqrt" function of that module doesn't work. What is the reason behind this? Can I fix it somehow?

Answer 1

You have two options:

import math
math.sqrt()

will import the math module into its own namespace. This means that function names have to be prefixed with math. This is good practice because it avoids conflicts and won't overwrite a function that was already imported into the current namespace.

Alternatively:

from math import *
sqrt()

will import everything from the math module into the current namespace. That can be problematic.

Answer 2

If you only import math to call sqrt function you need to do this:

In [1]: import math

In [2]: x = 2

In [3]: math.sqrt(x)
Out[3]: 1.4142135623730951

This is because from math import sqrt brings you the sqrt function, but import math only brings you the module.

Answer 3

When you only use import math the sqrt function comes in under a different name: math.sqrt.