Instance Property

exponent

The exponent of the floating-point value.

Declaration

var exponent: Int { get }

Discussion

The exponent of a floating-point value is the integer part of the logarithm of the value’s magnitude. For a value x of a floating-point type F, the magnitude can be calculated as the following, where ** is exponentiation:

let magnitude = x.significand * F.radix ** x.exponent

In the next example, y has a value of 21.5, which is encoded as 1.34375 * 2 ** 4. The significand of y is therefore 1.34375.

let y: Double = 21.5
// y.significand == 1.34375
// y.exponent == 4
// Double.radix == 2

The exponent property has the following edge cases:

  • If x is zero, then x.exponent is Int.min.

  • If x is +/-infinity or NaN, then x.exponent is Int.max

This property implements the logB operation defined by the IEEE 754 specification.

Relationships

From Protocol

See Also

Querying a Float

var ulp: Float

The unit in the last place of this value.

var significand: Float

The significand of the floating-point value.

var nextUp: Float

The least representable value that compares greater than this value.

var nextDown: Float

The greatest representable value that compares less than this value.

var binade: Float

The floating-point value with the same sign and exponent as this value, but with a significand of 1.0.