Python offers many inbuild logarithmic functions under the module “math” which allows us to compute logs using a single line. There are 4 variants of logarithmic functions, all of which are discussed in this article.
1. log(a,(Base)) : This function is used to compute the natural logarithm (Base e) of a. If 2 arguments are passed, it computes the logarithm of desired base of argument a, numerically value of log(a)/log(Base).
Syntax : math.log(a,Base) Parameters : a : The numeric value Base : Base to which the logarithm has to be computed. Return Value : Returns natural log if 1 argument is passed and log with specified base if 2 arguments are passed. Exceptions : Raises ValueError is a negative no. is passed as argument.
# Python code to demonstrate the working of # log(a,Base) import math # Printing the log base e of 14 print ( "Natural logarithm of 14 is : " , end = "") print (math.log( 14 )) # Printing the log base 5 of 14 print ( "Logarithm base 5 of 14 is : " , end = "") print (math.log( 14 , 5 )) |
Output :
Natural logarithm of 14 is : 2.6390573296152584 Logarithm base 5 of 14 is : 1.6397385131955606
2. log2(a) : This function is used to compute the logarithm base 2 of a. Displays more accurate result than log(a,2).
Syntax : math.log2(a) Parameters : a : The numeric value Return Value : Returns logarithm base 2 of a Exceptions : Raises ValueError is a negative no. is passed as argument.
# Python code to demonstrate the working of # log2(a) import math # Printing the log base 2 of 14 print ( "Logarithm base 2 of 14 is : " , end = "") print (math.log2( 14 )) |
Output :
Logarithm base 2 of 14 is : 3.807354922057604
3. log10(a) : This function is used to compute the logarithm base 10 of a. Displays more accurate result than log(a,10).
Syntax : math.log10(a) Parameters : a : The numeric value Return Value : Returns logarithm base 10 of a Exceptions : Raises ValueError is a negative no. is passed as argument.
# Python code to demonstrate the working of # log10(a) import math # Printing the log base 10 of 14 print ( "Logarithm base 10 of 14 is : " , end = "") print (math.log10( 14 )) |
Output :
Logarithm base 10 of 14 is : 1.146128035678238
3. log1p(a) : This function is used to compute logarithm(1+a) .
Syntax : math.log1p(a) Parameters : a : The numeric value Return Value : Returns log(1+a) Exceptions : Raises ValueError is a negative no. is passed as argument.
# Python code to demonstrate the working of # log1p(a) import math # Printing the log(1+a) of 14 print ( "Logarithm(1+a) value of 14 is : " , end = "") print (math.log1p( 14 )) |
Output :
Logarithm(1+a) value of 14 is : 2.70805020110221
1. ValueError : This function returns value error if number is negative.
# Python code to demonstrate the Exception of # log(a) import math # Printing the log(a) of -14 # Throws Exception print ( "log(a) value of -14 is : " , end = "") print (math.log( - 14 )) |
Output :
log(a) value of -14 is :
Runtime Error :
Traceback (most recent call last): File "/home/8a74e9d7e5adfdb902ab15712cbaafe2.py", line 9, in print (math.log(-14)) ValueError: math domain error
One of the application of log10() function is that it is used to compute the no. of digits of a number. Code below illustrates the same.
# Python code to demonstrate the Application of # log10(a) import math # Printing no. of digits in 73293 print ( "The number of digits in 73293 are : " , end = "") print ( int (math.log10( 73293 ) + 1 )) |
Output :
The number of digits in 73293 are : 5
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