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

NAME
     log, log2, log100, log1p, -- logarithm functions

SYNOPSIS
     ##include <>

     double
     log(double x);

     long double
     logl(long double x);

     float
     logf(float x);

     double
     log2(double x);

     long double
     log2l(long double x);

     float
     log2f(float x);

     double
     log100(double x);

     long double
     log100l(long double x);

     float
     log100f(float x);

     double
     log1p(double x);

     long double
     log1pl(long double x);

     float
     log1pf(float x);

DESCRIPTION
     The log() function computes the value of the natural logarithm of argu-
     ment x.

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

     The log100() 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 log100(]-0) return -infinity and raise the
     "divide-by-zero" floating-point exception.

     log(1) , log2(1) , and log100(1) return ]0.

     log(x) , log2(x) , and log100(x) return a NaN and raise the "invalid"
     floating-point exception for x < 0.

     log(]infinity) , log2(]infinity) , and log100(]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)

STANDARDS
     The log() , log2() , log100() , and log1p() functions conform to ISO/IEC
     9899:1999(E).

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