# log(3) [opendarwin man page]

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) returnand 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-infinityand raises the "divide-by-zero" floating-point exception. log1p(x) returns a NaN and raises the "invalid" floating-point exception for x <-infinitylog1p(+infinity) returns +infinity.-1.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 DistributionJuly 2, 2003 4th Berkeley Distribution

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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) returnand 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-infinityand raises the "divide-by-zero" floating-point exception. log1p(x) returns a NaN and raises the "invalid" floating-point exception for x <-infinitylog1p(+infinity) returns +infinity.-1.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 DistributionJuly 2, 2003 4th Berkeley Distribution