NAME

ilogb() − returns an unbiased exponent

SYNOPSIS

#include <math.h>

int ilogb(double x);

DESCRIPTION

The ilogb() function returns the exponent part of x. Formally, the return value is the integral part of log base r of |x| as a signed integral value, for nonzero x, where r is the radix of the machine’s floating point arithmetic.  The argument x is a double-precision floating-point value. 

Note: ilogb(x) is equivalent to (int)logb(x) for all values of x except NaN, ±INFINITY, and zero. 

To use this function, link in the math library by specifying −lm on the compiler or linker command line. 

RETURN VALUE

If x is NaN, ilogb() returns INT_MIN. 

If x is ±INFINITY, ilogb() returns INT_MAX. 

If x is zero, ilogb() returns INT_MIN. 

ERRORS

No errors are defined. 

SEE ALSO

scalb(3M), isinf(3M), isnan(3M), limits(5). 

STANDARDS CONFORMANCE

ilogb(): XPG4.2

Hewlett-Packard Company  —  HP-UX Release 10.20:  July 1996