Legacy Document

fmax

You can use the fmax function to find out which is the larger of two real numbers.

double_t fmax (double_t x, double_t y);

x

Any floating-point number.

y

Any floating-point number.

DESCRIPTION

The fmax function determines the larger of its two arguments.

$fmax(x,y)\; =\; x$ if x y
$fmax(x,y)\; =\; y$ if x < y

If one of the arguments is a NaN, the other argument is returned.

EXCEPTIONS

When x and y are finite and nonzero, the result of $fmax(x,y)$ is exact.

SPECIAL CASES

Table 10-2 shows the results when one of the arguments to the fmax function is a zero, a NaN, or an Infinity. In this table, x is a finite, nonzero floating-point number. (Note that the order of operands for this function does not matter.)

Special cases for the fmax function

Operation	Result	Exceptions raised
$fmax(+0,x)$	x if x > 0	None
	+0 if x < 0
$fmax(-0,x)$	x if x > 0	None
	$-0$ if x < 0
$fmax(\pm 0,\pm 0)$	+0	None
$fmax(NaN,x)$	x[21]	None[22]
$fmax(+$ ,x)	+	None
$fmax(-$ ,x)	x	None

EXAMPLES

z = fmax(-INFINITY, -300,000);   /* z = -300,000 because any 
                                    integer is greater than  */
z = fmax(NAN, -300,000);   /* z = -300,000 by definition of the
                              function fmax. */

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[21] If both arguments are NaNs, the first NaN is returned.

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[22] If the NaN is a signaling NaN, the invalid exception is raised.