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LOG(3)			    Library Functions Manual			LOG(3)

NAME
       log,  logf,  logl,  log10,  log10f,  log10l, log2, log2f, log2l,	log1p,
       log1pf, log1pl -- logarithm functions

LIBRARY
       Math Library (libm, -lm)

SYNOPSIS
       #include	<math.h>

       double
       log(double x);

       float
       logf(float x);

       long double
       logl(long double	x);

       double
       log10(double x);

       float
       log10f(float x);

       long double
       log10l(long double x);

       double
       log2(double x);

       float
       log2f(float x);

       long double
       log2l(long double x);

       double
       log1p(double x);

       float
       log1pf(float x);

       long double
       log1pl(long double x);

DESCRIPTION
       The log(), logf(), and logl() functions compute the  natural  logarithm
       of x.

       The  log10(),  log10f(),	 and  log10l() functions compute the logarithm
       base 10 of x, while log2(), log2f(), and	log2l()	compute	the  logarithm
       base 2 of x.

       The log1p(), log1pf(), and log1pl() functions compute the natural loga-
       rithm  of  1  + x.  Computing the natural logarithm as log1p(x) is more
       accurate	than computing it as log(1 + x)	when x is close	to zero.

RETURN VALUES
       These functions return the requested logarithm; the logarithm of	 1  is
       +0.   An	 attempt  to take the logarithm	of +-0 results in a divide-by-
       zero exception, and -infinity is	returned.   Otherwise,	attempting  to
       take the	logarithm of a negative	number results in an invalid exception
       and a return value of NaN.

SEE ALSO
       exp(3), ilogb(3), math(3), pow(3)

STANDARDS
       The   log(),  logf(),  logl(),  log10(),	 log10f(),  log10l(),  log2(),
       log2f(),	log2l(), log1p(), log1pf(), and	log1pl() functions conform  to
       ISO/IEC 9899:1999 ("ISO C99").

HISTORY
       The  log()  function  first appeared in Version 1 AT&T UNIX; log10() in
       Version 7 AT&T UNIX; log1p() in 4.3BSD.

FreeBSD	14.3			March 22, 2020				LOG(3)

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<https://man.freebsd.org/cgi/man.cgi?query=log2l&sektion=3&manpath=FreeBSD+14.3-RELEASE+and+Ports>

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