Skip to content
Related Articles

Related Articles

Python math library | expm1() method
  • Last Updated : 31 Oct, 2018

Python has math library and has many functions regarding to it. One such function is expm1(). This function mathematically computes the value of exp(x) - 1. This method can be used if we need to compute this very value.

Syntax : math.expm1()

Parameters :
x : Number whose exp(x)-1 has to be computed.

Returns : Returns the computed value of “exp(x)-1”

Code #1 : Demonstrate the working of expm1()






# Python3 code to demonstrate
# the working of expm1()
import math
  
# initializing the value 
test_int = 4
test_neg_int = -3
  
# checking expm1() values
# doesn't throw error with negative
print ("The expm1 value using positive integer : "
                      + str(math.expm1(test_int)))
                        
print ("The expm1 value using negative integer : "
                  + str(math.expm1(test_neg_int)))

Output :

The expm1 value using positive integer : 53.598150033144236
The expm1 value using negative integer : -0.950212931632136

 

“exp() – 1” vs “expm1()”

There would be a question why expm1() method was even created if we could always compute exp() and then subtract 1 from it. The first reason is that value exp() - 1 is used a lot in mathematics and science applications and formulas.
The most important reason is that for smaller value of x, of the order less than e-10, expm1() method give a result more accurate than exp() - 1.

Code #2 : Comparing expm1() and exp()-1




# Python3 code to demonstrate
# the application of expm1()
import math
  
# initializing the value 
test_int = 1e-10
  
# checking expm1() values
# expm1() is more accurate
print ("The value with exp()-1  : " + str(math.exp(test_int)-1))
print ("The value with expm1() : " + str(math.expm1(test_int)))

Output :

The value with exp()-1  : 1.000000082740371e-10
The value with expm1() : 1.00000000005e-10

 Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.  

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course. And to begin with your Machine Learning Journey, join the Machine Learning – Basic Level Course

My Personal Notes arrow_drop_up
Recommended Articles
Page :