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”Time Complexity: O(1)
Auxiliary Space: O(1)
Code #1 : Demonstrate the working of expm1()
Python3
# Python3 code to demonstrate# the working of expm1()import math# initializing the valuetest_int = 4test_neg_int = -3# checking expm1() values# doesn't throw error with negativeprint ("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
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
# Python3 code to demonstrate# the application of expm1()import math# initializing the valuetest_int = 1e-10# checking expm1() values# expm1() is more accurateprint ("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
