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log1p, log1pf
[log of 1 + x]

SYNOPSIS

    #include <math.h>
    double log1p(double x);
    float log1pf(float x);

DESCRIPTION

log1p calculates ln(1+x), the natural logarithm of 1+x. You can use log1p rather than log(1+x) for greater precision when x is very small.

log1pf calculates the same thing, but accepts and returns float values rather than double.

RETURNS

log1p returns a double, the natural log of 1+x. log1pf returns a float, the natural log of 1+x.

COMPLIANCE

Neither log1p nor log1pf is required by ANSI C or by the System V Interface Definition (Issue 2).