opensolaris man page for log1pl

log1p(3M)						  Mathematical Library Functions						 log1p(3M)

NAME
       log1p, log1pf, log1pl - compute natural logarithm

SYNOPSIS
       c99 [ flag... ] file... -lm [ library... ]
       #include <math.h>

       double log1p(double x);

       float log1pf(float x);

       long double log1pl(long double x);

DESCRIPTION
       These functions compute log(e)(1.0 + x).

RETURN VALUES
       Upon successful completion, these functions return the natural logarithm of 1.0 + x.

       If x is -1, a pole error occurs and log1p(), log1pf(), and log1pl() return -HUGE_VAL, -HUGE_VALF, and -HUGE_VALL, respectively.

       For finite values of x that are less than -1, or if x is -Inf, a domain error occurs and a NaN is returned.

       If x is NaN, a NaN is returned.

       If x is +-0 or +Inf, x is returned.

       For exceptional cases, matherr(3M) tabulates the values to be returned by log1p() as specified by SVID3 and XPG3.

ERRORS
       These functions will fail if:

       Domain Error    The finite value of x is less than -1, or x is -Inf.

		       If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, the invalid floating-point exception is raised.

		       The log1p() function sets errno to EDOM if the value of x is less than -1.

       Pole Error      The value of x is -1.

		       If  the	integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, the divide-by-zero floating-point exception is
		       raised.

USAGE
       An application wanting to check for exceptions should call feclearexcept(FE_ALL_EXCEPT) before  calling	these  functions.  On  return,	if
       fetestexcept(FE_INVALID	|  FE_DIVBYZERO  |  FE_OVERFLOW  |  FE_UNDERFLOW) is non-zero, an exception has been raised. An application should
       either examine the return value or check the floating point exception flags to detect exceptions.

       An application can also set errno to 0 before calling log1p(). On return, if errno is non-zero, an error has  occurred.	The  log1pf()  and
       log1pl() functions do not set errno.

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO
       feclearexcept(3M), fetestexcept(3M), log(3M), math.h(3HEAD), matherr(3M), attributes(5), standards(5)

SunOS 5.11							    12 Jul 2006 							 log1p(3M)