log1p(3) [php man page]

LOG1P(3)								 1								  LOG1P(3)

log1p - Returns log(1 + number), computed in a way that is accurate even when the value of number is close to zero

SYNOPSIS

       float log1p (float  $number)

DESCRIPTION

       log1p(3)  returns  log(1  +  $number) computed in a way that is accurate even when the value of $number is close to zero. log(3) might only
       return log(1) in this case due to lack of precision.

PARAMETERS

	      o $number
		- The argument to process

RETURN VALUES

	log(1 + $number)

CHANGELOG

       +--------+--------------------------------------------------+
       |Version |						   |
       |	|						   |
       |	|		    Description 		   |
       |	|						   |
       +--------+--------------------------------------------------+
       | 5.3.0	|						   |
       |	|						   |
       |	|  This function is now available on all platforms |
       |	|						   |
       +--------+--------------------------------------------------+
SEE ALSO

       expm1(3), log(3), log10(3).

PHP Documentation Group 														  LOG1P(3)

LOG1P(3)						     Linux Programmer's Manual							  LOG1P(3)

NAME

       log1p, log1pf, log1pl -	logarithm of 1 plus argument

SYNOPSIS

       #include <math.h>

       double log1p(double x);
       float log1pf(float x);
       long double log1pl(long double x);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       log1p(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE; or cc -std=c99
       log1pf(), log1pl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or cc -std=c99

DESCRIPTION

       log1p(x) returns a value equivalent to

	   log (1 + x)

       It is computed in a way that is accurate even if the value of x is near zero.

RETURN VALUE

       On success, these functions return the natural logarithm of (1 + x).

       If x is a NaN, a NaN is returned.

       If x is positive infinity, positive infinity is returned.

       If x is -1, a pole error occurs, and the functions return -HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, respectively.

       If x is less than -1 (including negative infinity), a domain error occurs, and a NaN (not a number) is returned.

ERRORS

       See math_error(7) for information on how to determine whether an error has occurred when calling these functions.

       The following errors can occur:

       Domain error: x is less than -1
	      An invalid floating-point exception (FE_INVALID) is raised.

       Pole error: x is -1
	      A divide-by-zero floating-point exception (FE_DIVBYZERO) is raised.

       These functions do not set errno.

CONFORMING TO

       C99, POSIX.1-2001.

SEE ALSO

       exp(3), expm1(3), log(3)

COLOPHON

       This  page is part of release 3.25 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

								    2008-08-05								  LOG1P(3)