Web4 days ago · Definition: Logarithmic Function. A logarithmic function is the inverse of an exponential function. For the exponential function 𝑓 ( 𝑥) = 𝑎 , its inverse logarithmic function is 𝑓 ( 𝑥) = 𝑥 l o g or 𝑔 ( 𝑥) = 𝑥 l o g . If the point ( 𝑥, 𝑦) satisfies the exponential function, then the point ( 𝑦, 𝑥) satisfies the logarithmic function.