Logarithmic derivative

In mathematics, specifically in calculus and complex analysis, the logarithmic derivative of a function f is defined by the formula

Related Topics:
Mathematics - Calculus - Complex analysis - Function

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:f′/f

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where f′ is the derivative of f.

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When f is a function f(x) of a real variable x, and takes real, strictly positive values, this is indeed the formula for (log f)′, that is, the derivative of the natural logarithm of f, as follows from the chain rule.

Related Topics:
Positive - Natural logarithm - Chain rule

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