log(3) [php man page]

LOG(3)									 1								    LOG(3)

log - Natural logarithm

SYNOPSIS

       float log (float  $arg, [float  $base = M_E])

DESCRIPTION

	If the optional $base parameter is specified, log(3) returns logbase$arg, otherwise log(3) returns the natural logarithm of $arg.

PARAMETERS

	      o $arg
		- The value to calculate the logarithm for

	      o $base
		- The optional logarithmic base to use (defaults to 'e' and so to the natural logarithm).

RETURN VALUES

	The logarithm of $arg to $base, if given, or the natural logarithm.

SEE ALSO

       log10(3), exp(3), pow(3).

PHP Documentation Group 														    LOG(3)

LOG(3)							   BSD 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 logarithm 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'').

BSD
								   June 3, 2013 							       BSD