opendarwin man page for log

LOG(3)							   BSD Library Functions Manual 						    LOG(3)

NAME
     log, log2, log10, log1p, -- logarithm functions

SYNOPSIS
     #include <math.h>

     double
     log(double x);

     double
     log2(double x);

     double
     log10(double x);

     double
     log1p(double x);

DESCRIPTION
     The log() function computes the value of the natural logarithm of argument x.

     The log2() function computes the value of the logarithm of argument x to base 2.

     The log10() function computes the value of the logarithm of argument x to base 10.

     The log1p() function computes the value of log(1+x) accurately even for very small values of x.

SPECIAL VALUES
     log(+-0) , log2(+-0) , and log10(+-0) return -infinity and raise the "divide-by-zero" floating-point exception.

     log(1) , log2(1) , and log10(1) return +0.

     log(x) , log2(x) , and log10(x) return a NaN and raise the "invalid" floating-point exception for x < 0.

     log(+infinity) , log2(+infinity) , and log10(+infinity) return +infinity.

     log1p(+-0) returns +-0.

     log1p(-1) returns -infinity and raises the "divide-by-zero" floating-point exception.

     log1p(x) returns a NaN and raises the "invalid" floating-point exception for x < -1.

     log1p(+infinity) returns +infinity.

SEE ALSO
     math(3), exp(3), exp2(3), expm1(3), pow(3), infnan(3)

STANDARDS
     The log() , log2() , log10() , and log1p() functions conform to ISO/IEC 9899:1999(E).

4th Berkeley Distribution					   July 2, 2003 					 4th Berkeley Distribution