# 5.4. Math functions¶

Python has a `math`

module that provides most of the familiar
mathematical functions. Before we can use the module, we have to import
it:

```
>>> import math
```

This statement creates a *module object* named math. If
you print the module object, you get some information about it:

The module object contains the functions and variables defined in the
module. To access one of the functions, you have to specify the name of
the module and the name of the function, separated by a dot (also known
as a period). This format is called *dot notation*.

The first example computes the logarithm base 10 of the signal-to-noise
ratio. The math module also provides a function called `log`

that computes logarithms base e.

The second example finds the sine of `radians`

. The name of
the variable is a hint that `sin`

and the other trigonometric
functions (`cos`

, `tan`

, etc.) take arguments in
radians. To convert from degrees to radians, divide by 360 and multiply
by 2pi:

The expression `math.pi`

gets the variable `pi`

from the math module. The value of this variable is an approximation of
pi, accurate to about 15 digits.

If you know your trigonometry, you can check the previous result by comparing it to the square root of two divided by two:

- import math
- Correct! import math allows you to use the math module by creating the "math" module object.
- include math
- Incorrect! include works similarly to import, but it's not what we're using. Try again.
- add math
- Incorrect! add will not import the math module. Try again.
- None. You can always use the math module.
- Incorrect! Something needs to be done to allow the math module to be used. Try again.

p9-5: Which statement allows you to use the math module in Python?

- log
- Incorrect! log is a function within the math module. Try again.
- quotation marks or single quotes
- Incorrect! You need these to create a string. Try again.
- dot notation
- Correct! Dot notation allows us to access a function in a module.
- function notation
- Incorrect! Function notation is the way a function is written. Try again.

p9-6: To access a function in a module, we must use…

p9-7: When we use the “import math” statement, a __________ called math is created.