HP-UX Reference (11i v1 00/12) - 3 Library Functions A-M (vol 6)

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STANDARD Printed by: Nora Chuang [nchuang] STANDARD
/build/1111/BRICK/man3/!!!intro.3c
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i
ilogb(3M) ilogb(3M)
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.
The ISO/ANSI C committee has approved the ilogb() function for inclusion in the C9X draft standard.
To use this function, compile either with the default -Ae option or with the -Aa and -D_HPUX_SOURCE
options. Make sure your program includes <math.h>. 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
logb(3M), scalb(3M), scalbn(3M), math(5), limits(5).
STANDARDS CONFORMANCE
ilogb():XPG4.2
HP-UX Release 11i: December 2000 − 1 − Section 3−−441
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