The Logarithmic derivative is also something that is surprisingly fundamental. (ln(f))' = f'/f In function theory you use it all the time. But people rarely n

The Logarithmic derivative is also something that is surprisingly fundamental. (ln(f))' = f'/f In function theory you use it all the time. But people rarely notice, that it related to a logarithm. Also the functions that have nice logarithmic derivative are a lot more interesting than expected. Nature is full of Gompertz functions. Once you're familiar with it, you see it everywhere.