NAME

frexp, ldexp, modf − manipulate parts of floating-point numbers

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 (defined in <math.h> ) 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. 

March 13, 1992