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C++ Programming/Code/Standard C Library/Functions/log
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log
#include <cmath>
double log( double num );
The function log() returns the natural (base e) logarithm of num. There's a domain error if num is negative, a range error if num is zero.
In order to calculate the logarithm of x to an arbitrary base b, you can use:
double answer = log(x) / log(b);
Related topics exp - log10 - pow - sqrt