IsInfinite

Reports whether a value is one of the two infinities.

Module: Format

Signature

func IsInfinite(value: float64) -> bool;
func IsInfinite(value: float32) -> bool;

Parameters

Name	Type	Description
value	float64 / float32	The value to test.

Returns

true for the positive infinity and for the negative one, and false for every finite value. The sign is not reported — compare against zero for that.

The test is a comparison against the largest finite value of the type, so the width matters: the overload is chosen by the argument, and a float32 infinity is measured against the float32 range rather than being widened into the far larger float64 one and found finite there.

A NaN answers false. Every comparison against a NaN is false, so it fails this test rather than being mistaken for an infinity.

Example

import Format::IsInfinite;

let inf = 1.0 / 0.0;

IsInfinite(inf);                    // true
IsInfinite(-inf);                   // true
IsInfinite(0.0 / 0.0);              // false -- a NaN is not an infinity
IsInfinite(1.7976931348623157e308); // false -- the largest finite float64

if IsInfinite(inf) && inf < 0.0 {
    // the negative one
}

See also

• Format — the module overview
• IsNan — whether the value is a NaN
• IsFinite — whether the value is an ordinary number
• ToString — the infinities convert to the text Inf and -Inf