Python math.ulp() – Least Significant Bit

Python math.ulp()

math.ulp(x) function returns the least significant bit of the float value x.

Syntax

The syntax to call ulp() function is

math.ulp(x)

where

math.ulp() function is new in Python version 3.9.

Examples

1. Least significant bit of a float value

In the following program, we find the least significant bit of float x=3.1415.

import math

x = 3.1415
result = math.ulp(x)
print('ulp(x) :', result)

Output

ulp(x) : 4.440892098500626e-16

2. Least significant bit of a negative float value

In the following program, we find the least significant bit of negative float x=-3.1415. If x is negative value, then math.ulp() returns ulp(-x).

import math

x = -3.1415
result = math.ulp(x)
print('ulp(x) :', result)

Output

ulp(x) : 4.440892098500626e-16

3. Least significant bit of infinity

In the following program, we find the least significant bit of x=infinity. math.ulp() returns infinity.

import math

x = math.inf
result = math.ulp(x)
print('ulp(x) :', result)

Output

ulp(x) : inf

4. Least significant bit of nan

In the following program, we find the least significant bit of x=NaN. math.ulp() returns nan.

import math

x = math.nan
result = math.ulp(x)
print('ulp(x) :', result)

Output

ulp(x) : nan

5. Least significant bit of 0

In the following program, we find the least significant bit of float x=0. math.ulp() returns smallest positive denormalised representable float.

import math

x = 0
result = math.ulp(x)
print('ulp(x) :', result)

Output

ulp(x) : 5e-324

Summary

In this Python Math tutorial, we learned the syntax of, and examples for math.trunc() function.