NAME

logb, logbf, logbl, scalb, scalbf, scalbl, significand, significandf — IEEE test functions

SYNOPSIS

/* -lm */
#include <math.h>

double
logb(double x);

float
logbf(float x);

long double
logbl(long double x);

double
scalb(double x, double n);

float
scalbf(float x, float n);

long double
scalbl(long double x, long double n);

double
significand(double x);

float
significandf(float x);

DESCRIPTION

These functions allow users to test conformance to IEEE Std 754-1985. Their use is not otherwise recommended.

logb(x) returns x's exponent n, a signed integer converted to double-precision floating-point. logb(±infinity) = +infinity; logb(0) = -infinity with a division by zero exception. logbf() is the single precision form of logb(). logbl() is the extended precision form of logb().

scalb(x, n) returns x*(2**n) computed by exponent manipulation. scalbf() is the single precision form of scalb(). scalbl() is the extended precision form of scalb().

significand(x) returns sig, where x := sig * 2**n with 1 ≤ sig < 2. significand(x) is not defined when x is 0, ±infinity, or NaN. significandf() is the single precision for of significand().

SEE ALSO

fpclassify(3), ilogb(3), scalbn(3)

STANDARDS

IEEE Std 754-1985