ieee_test(3)                                               ieee_test(3)

  ieee_test()

  NAME

    logb(), scalb(), significand() - IEEE test functions

  SYNOPSIS

    #include 

    double logb (double x)

    double scalb (double x, double n)

    double significand (double x)

  DESCRIPTION

    These functions allow users to test conformance to the IEEE 754 standard.

    logb(3) returns the exponent n of the argument x, n is a signed integer
    converted to double-precision floating-point. Specifically, it's the
    integral part of logr |x|, where r is the radix of the machine's floating
    point arithmetic. logb(+-Infinity) = +Infinity; logb(0) = -Infinity with a
    division by zero exception.

    The scalb(x,n) function returns x(r**n), where r is the radix of the
    machine's floating point arithmetic. (For r=2, this is identical to
    ldexp(3).) The value is computed by exponent manipulation without first
    computing r**n.

    significand(3) returns sig, where the argument x := sig*2**n with 1 <= sig
    < 2. The significand() value are not defined when x is 0, +-Infinity, or
    NaN.

  RETURN VALUES

    The logb() function returns the exponent of x. If x is zero, it returns -
    HUGE_VAL and sets errno. If x is +-Infinity, it returns Infinity. If x is
    NaN, it returns NaN and sets errno.

    The scalb(3) function returns the value x(r**n) where r is the radix of
    the machine's floating point arithmetic.

  ERRORS

    The logb(3) function can fail for the following reasons:

    [EDOM]
        Either the x argument is zero, or it is NaN.

    The scalb(3) function can fail for the following reasons:

    [EDOM]
        Either x or n is NaN.

    [ERANGE]
        The correct value will overflow or underflow.

  NOTES

    Note that the function ldexp(3) is slightly more portable than scalb(3),
    and that frexp(3) does the same jobs as scalb(3) and significand(3), in a
    slightly more portable manner. Both ldexp(3) and frexp(3) use the radix as
    base for the exponent, rather than 2.

  SEE ALSO

    frexp(3)

    ieee(3)

    ldexp(3)

    math(3)

  USAGE NOTES

    All of these functions are thread safe.

    None of these functions are async-signal safe.