The antilog of a number is the inverse of the log of a number.
So, if you calculate the log of a number you can then use the antilog to get back the original number.
For example, suppose we start with the number 7. If we take the log (base 10) of 7 then we would get .845:
log10(7) = .845
The antilog (base 10) of the value 0.845 can be found by taking 10 raised to the power of 0.845:
10.845 = 7
The antilog allowed us to get back the original number.
The following table shows how to calculate the antilog of values in Python according to their base:
| Base | Number | Log | Antilog |
|---|---|---|---|
| e | x | np.log(x) | np.exp(x) |
| 10 | x | np.log10(x) | 10 ** x |
The following examples show how to calculate the antilog of values in Python using different values for the base.
Example 1: Calculating the Antilog of Base 10
Suppose we take the log (base 10) of the value 7:
import numpy as np #define original value original = 7 #take log (base 10) of original value log_original = np.log10(original) #display log (base 10) of original value log_original 0.845098
In order to get back the original value of 7, we can take the antilog by raising 10 to the power of 0.845098:
#take the antilog 10 ** log_original 7.0
By taking the antilog, we were able to obtain the original value of 7.
Example 2: Calculating the Antilog of a Natural Log
Suppose we take the natural log of the value 7:
#define original value original = 7 #take natural log of original value log_original = np.log(original) #display natural log of original value log_original [1] 1.94591
In order to get back the original value of 7, we can take the antilog by raising e to the power of 1.94591:
#take the antilog np.exp(log_original) 7.0
By taking the antilog, we were able to obtain the original value of 7.
Additional Resources
How to Create a Log-Log Plot in Python
How to Perform a Box-Cox Transformation in Python