logb(3M)
NAME
logb − radix-independent exponent
SYNOPSIS
cc [ flag ... ] file ... −lm [ library ... ]
#include <math.h>
double logb(double x);
DESCRIPTION
The logb() function computes the exponent of x, which is the integral part of logr │x│, as a signed floating point value, for non-zero x, where r is the radix of the machine’s floating-point arithmetic.
RETURN VALUES
Upon successful completion, logb() returns the exponent of x.
If x is 0.0, logb() returns −HUGE_VAL and sets errno to EDOM.
If x is ±Inf, logb() returns +Inf.
If x is NaN, logb() returns NaN.
For exceptional cases, matherr(3M) tabulates the values to be returned as dictated by various Standards.
ERRORS
The logb() function will fail if:
EDOM The x argument is 0.0.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| MT-Level | MT-Safe |
SEE ALSO
ilogb(3M), matherr(3M), attributes(5)
SunOS 5.6 — Last change: 29 Dec 1996