log,
logf
[natural logarithms]
SYNOPSIS
#include <math.h> double log(double x); float logf(float x);
DESCRIPTION
Return the natural logarithm
of x,
that is, its logarithm base e (where e is the base of the
natural system of logarithms, 2.71828: : :).
log
and logf
are identical save for the return and
argument types.
You can use the (non-ANSI) function matherr to specify error handling for these functions.
RETURNS
Normally, returns the calculated
value. When x
is zero, the returned value is -HUGE_VAL
and errno
is set to ERANGE.
When x
is negative, the returned value is
-HUGE_VAL
and errno
is set to EDOM.
You can control the error behavior via matherr.
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1db
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COMPLIANCE
log
is ANSI, logf
is an extension.