# Python math.atan2() Method

Musfirah Waseem Sep 16, 2022

Python `math.atan2()` method is an efficient way of calculating the arctangent of a number, `x`, in radians. The value returned represents the angle `theta` of a point (`x`, `y`) and the positive `x-axis`.

## Syntax

``````math.atan2(y, x)
``````

## Parameters

`y` Any positive or negative value.
`x` Any positive or negative value.

## Return

The return type for this method is a `float` value representing the arctangent of a `theta` in radians. The value returned is in the range `-PI` and `PI.`

## Examples

### Demonstrate the Correct Use of Python `math.atan2()` Method

Code Snippet One:

``````import math

y = 0.334
x = -0.9
value = math.atan2(y, x)
print(f"The arctangent of {y},{x} is {value}.")

y = 100.0
x = 1
value = math.atan2(y, x)
print(f"The arctangent of {y},{x} is {value}.")

y = -0.03
x = 1087
value = math.atan2(y, x)
print(f"The arctangent of {y},{x} is {value}.")
``````

Output:

``````The arctangent of 0.334,-0.9 is 2.7862357715696127.
The arctangent of 100.0,1 is 1.5607966601082315.
The arctangent of -0.03,1087 is -2.7598896037150882e-05.
``````

Note that the parameters should be `float` values. The values may be either positive or negative.

Code Snippet Two:

``````import math

y = [2, 4, 6]
x = [1, -4, 100]

for i in range(len(x)):
value = math.atan2(y[i], x[i])
print(f"The arctangent of {y},{x} is {value}.")
``````

Output:

``````The arctangent of [2, 4, 6],[1, -4, 100] is 1.1071487177940904.
The arctangent of [2, 4, 6],[1, -4, 100] is 2.356194490192345.
The arctangent of [2, 4, 6],[1, -4, 100] is 0.05992815512120789.
``````

Note that we can use this method to find the slope in radians when `y` and `x` coordinates are given.

### Demonstrate an Error While Using the `math.atan2()` Method

Code Snippet:

``````import math

y = 0
x = 1
value = math.atan2([y], [x])
print(f"The arctangent of {y},{x} is {value}.")
``````

Output:

``````Traceback (most recent call last):
File "main.py", line 7, in <module>
value=math.atan2([y],[x])
TypeError: must be the real number, not a list
``````

Note that a `TypeError` exception may occur if the argument value is not a `float`.

Musfirah is a student of computer science from the best university in Pakistan. She has a knack for programming and everything related. She is a tech geek who loves to help people as much as possible.