FREXP(3C)

NAME

frexp, ldexp, modf − split floating-point into mantissa and exponent

SYNOPSIS

double frexp (value, eptr)
double value;
int ∗eptr;

double ldexp (value, exp)
double value;
int exp;

double modf (value, iptr)
double value, ∗iptr;

DESCRIPTION

Every non-zero number can be written uniquely as x∗ 2n, where the “mantissa” (fraction) x is in the range 0.5 ≤ |x| < 1.0, and the “exponent” n is an integer.

Frexp returns the mantissa of a double value, and stores the exponent indirectly in the location pointed to by eptr. If value is zero, both results returned by frexp are zero.

Ldexp returns the quantity value∗ 2exp.

Modf returns the signed fractional part of value and stores the integral part indirectly in the location pointed to by iptr.

DIAGNOSTICS

If ldexp would cause overflow, ±HUGE is returned (according to the sign of value), and errno is set to ERANGE.
If ldexp would cause underflow, zero is returned and errno is set to ERANGE.

STANDARDS CONFORMANCE

frexp: SVID2, XPG2, XPG3, POSIX.1, FIPS 151-1, ANSI C

ldexp: SVID2, XPG2, XPG3, POSIX.1, FIPS 151-1, ANSI C

modf: SVID2, XPG2, XPG3, POSIX.1, FIPS 151-1, ANSI C