IsFinite

Reports whether a value is an ordinary number.

Module: Format

Signature

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

Parameters

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

Returns

true when the value is neither a NaN nor an infinity: every real number the type can hold, from the largest finite value down through the subnormals to zero, and the negative of each.

This is exactly the negation of IsNan or IsInfinite — the three partition the values, and every value answers true to precisely one of them. A NaN is not finite: the test is a pair of comparisons against the range of the type, and every comparison against a NaN is false.

As with IsInfinite, the width matters, and the overload is chosen by the argument. A float32 is measured against the float32 range.

Example

import Format::IsFinite;

IsFinite(0.0);                    // true
IsFinite(-1.5e300);               // true
IsFinite(5.0e-324);               // true -- the smallest subnormal is still a number
IsFinite(1.0 / 0.0);              // false
IsFinite(0.0 / 0.0);              // false

IsFinite(3.4028235e38f32);        // true  -- the largest finite float32
IsFinite(1.0e300);                // true  -- as a float64

See also

• Format — the module overview
• IsNan — whether the value is a NaN
• IsInfinite — whether the value is one of the two infinities
• ToString — what each of the three classes prints as