What is math.atan2() in Python?

Overview

This math.atan2() method is used to calculate the arctangent of y/x, in radians, where x and y are coordinates of a point (x,y) in the cartesian plane.


The value returned by this function is between and π.

atan2(y,x)

Syntax


math.atan2(y, x)

Parameters

This method accepts positive and negative numeric values.

  • y: the first parameter
  • x: the second parameter

Return value

This method returns a primitive float value, representing the arc tangent x/y in radians, between and π.


This angle θ returned by this method is from polar coordinate (r,θ).

Code

import math
# Two positive coordinates
print(math.atan2(3, 4))
# Two negative coordinates
print(math.atan2(-3, -4))
# One positive and One negative coordinate
print(math.atan2(3.4, -3.1))

TypeError

This method will generate an error when we pass integer arguments.

It’s also Python version-dependent.

  • Python 3: TypeError: a float is required.

  • Python 3.8: TypeError: must be a real number, not a list.

Example 1: Python 3 TypeError

import math
# It will generate type error on integer argument
y, x = 2, 3
theeta = math.atan2([y], [x])
print(theeta)

Example 2: Python 3.8 TypeError

import math
# It will generate type error on integer argument
y, x = 2, 3
theeta = math.atan2([y], [x])
print(theeta)

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