FloatingPoint

`protocol FloatingPoint`

A floating-point numeric type.

Floating-point types are used to represent fractional numbers, like 5.5, 100.0, or 3.14159274. Each floating-point type has its own possible range and precision. The floating-point types in the standard library are `Float`, `Double`, and `Float80` where available.

Create new instances of floating-point types using integer or floating-point literals. For example:

``````let temperature = 33.2
let recordHigh = 37.5``````

The `FloatingPoint` protocol declares common arithmetic operations, so you can write functions and algorithms that work on any floating-point type. The following example declares a function that calculates the length of the hypotenuse of a right triangle given its two perpendicular sides. Because the `hypotenuse(_:_:)` function uses a generic parameter constrained to the `FloatingPoint` protocol, you can call it using any floating-point type.

``````func hypotenuse<T: FloatingPoint>(_ a: T, _ b: T) -> T {
return (a * a + b * b).squareRoot()
}

let (dx, dy) = (3.0, 4.0)
let distance = hypotenuse(dx, dy)
// distance == 5.0``````

Floating-point values are represented as a sign and a magnitude, where the magnitude is calculated using the type's radix and the instance's significand and exponent. This magnitude calculation takes the following form for a floating-point value `x` of type `F`, where `**` is exponentiation:

``x.significand * F.radix ** x.exponent``

Here's an example of the number -8.5 represented as an instance of the `Double` type, which defines a radix of 2.

``````let y = -8.5
// y.sign == .minus
// y.significand == 1.0625
// y.exponent == 3

let magnitude = 1.0625 * Double(2 ** 3)
// magnitude == 8.5``````

Types that conform to the `FloatingPoint` protocol provide most basic (clause 5) operations of the IEEE 754 specification. The base, precision, and exponent range are not fixed in any way by this protocol, but it enforces the basic requirements of any IEEE 754 floating-point type.

In addition to representing specific numbers, floating-point types also have special values for working with overflow and nonnumeric results of calculation.

Infinity

Any value whose magnitude is so great that it would round to a value outside the range of representable numbers is rounded to infinity. For a type `F`, positive and negative infinity are represented as `F.infinity` and `-F.infinity`, respectively. Positive infinity compares greater than every finite value and negative infinity, while negative infinity compares less than every finite value and positive infinity. Infinite values with the same sign are equal to each other.

``````let values: [Double] = [10.0, 25.0, -10.0, .infinity, -.infinity]
print(values.sorted())
// Prints "[-inf, -10.0, 10.0, 25.0, inf]"``````

Operations with infinite values follow real arithmetic as much as possible: Adding or subtracting a finite value, or multiplying or dividing infinity by a nonzero finite value, results in infinity.

NaN ("not a number")

Floating-point types represent values that are neither finite numbers nor infinity as NaN, an abbreviation for "not a number." Comparing a NaN with any value, including another NaN, results in `false`.

``````let myNaN = Double.nan
print(myNaN > 0)
// Prints "false"
print(myNaN < 0)
// Prints "false"
print(myNaN == .nan)
// Prints "false"``````

Because testing whether one NaN is equal to another NaN results in `false`, use the `isNaN` property to test whether a value is NaN.

``````print(myNaN.isNaN)
// Prints "true"``````

NaN propagates through many arithmetic operations. When you are operating on many values, this behavior is valuable because operations on NaN simply forward the value and don't cause runtime errors. The following example shows how NaN values operate in different contexts.

Imagine you have a set of temperature data for which you need to report some general statistics: the total number of observations, the number of valid observations, and the average temperature. First, a set of observations in Celsius is parsed from strings to `Double` values:

``````let temperatureData = ["21.5", "19.25", "27", "no data", "28.25", "no data", "23"]
let tempsCelsius = temperatureData.map { Double(\$0) ?? .nan }
// tempsCelsius == [21.5, 19.25, 27, nan, 28.25, nan, 23.0]``````

Note that some elements in the `temperatureData ` array are not valid numbers. When these invalid strings are parsed by the `Double` failable initializer, the example uses the nil-coalescing operator (`??`) to provide NaN as a fallback value.

Next, the observations in Celsius are converted to Fahrenheit:

``````let tempsFahrenheit = tempsCelsius.map { \$0 * 1.8 + 32 }
// tempsFahrenheit == [70.7, 66.65, 80.6, nan, 82.85, nan, 73.4]``````

The NaN values in the `tempsCelsius` array are propagated through the conversion and remain NaN in `tempsFahrenheit`.

Because calculating the average of the observations involves combining every value of the `tempsFahrenheit` array, any NaN values cause the result to also be NaN, as seen in this example:

``````let badAverage = tempsFahrenheit.reduce(0.0, combine: +) / Double(tempsFahrenheit.count)

Instead, when you need an operation to have a specific numeric result, filter out any NaN values using the `isNaN` property.

``````let validTemps = tempsFahrenheit.filter { !\$0.isNaN }
let average = validTemps.reduce(0.0, combine: +) / Double(validTemps.count)``````

Finally, report the average temperature and observation counts:

``````print("Average: \(average)°F in \(validTemps.count) " +
"out of \(tempsFahrenheit.count) observations.")
// Prints "Average: 74.84°F in 5 out of 7 observations."``````
Inheritance `AbsoluteValuable, Arithmetic, Comparable, Equatable, ExpressibleByIntegerLiteral, SignedNumber, Strideable` View Protocol Hierarchy → `Exponent : SignedInteger` A type that represents any written exponent. `Magnitude : Equatable, ExpressibleByIntegerLiteral` `IntegerLiteralType` A type that represents an integer literal. The standard library integer and floating-point types are all valid types for `IntegerLiteralType`. `Stride : SignedNumber` A type that represents the distance between two values of `Self`. `import Swift`

Initializers

init(_: Int) Required

Creates a new value, rounded to the closest possible representation.

If two representable values are equally close, the result is the value with more trailing zeros in its significand bit pattern.

`value`: The integer to convert to a floating-point value.

Declaration

`init(_ value: Int)`
init(_: Int8) Required

Creates a new value, rounded to the closest possible representation.

If two representable values are equally close, the result is the value with more trailing zeros in its significand bit pattern.

`value`: The integer to convert to a floating-point value.

Declaration

`init(_ value: Int8)`
init(_: Int16) Required

Creates a new value, rounded to the closest possible representation.

If two representable values are equally close, the result is the value with more trailing zeros in its significand bit pattern.

`value`: The integer to convert to a floating-point value.

Declaration

`init(_ value: Int16)`
init(_: Int32) Required

Creates a new value, rounded to the closest possible representation.

If two representable values are equally close, the result is the value with more trailing zeros in its significand bit pattern.

`value`: The integer to convert to a floating-point value.

Declaration

`init(_ value: Int32)`
init(_: Int64) Required

Creates a new value, rounded to the closest possible representation.

If two representable values are equally close, the result is the value with more trailing zeros in its significand bit pattern.

`value`: The integer to convert to a floating-point value.

Declaration

`init(_ value: Int64)`
init(_: UInt) Required

Creates a new value, rounded to the closest possible representation.

If two representable values are equally close, the result is the value with more trailing zeros in its significand bit pattern.

`value`: The integer to convert to a floating-point value.

Declaration

`init(_ value: UInt)`
init(_: UInt8) Required

Creates a new value, rounded to the closest possible representation.

If two representable values are equally close, the result is the value with more trailing zeros in its significand bit pattern.

`value`: The integer to convert to a floating-point value.

Declaration

`init(_ value: UInt8)`
init(_: UInt16) Required

Creates a new value, rounded to the closest possible representation.

If two representable values are equally close, the result is the value with more trailing zeros in its significand bit pattern.

`value`: The integer to convert to a floating-point value.

Declaration

`init(_ value: UInt16)`
init(_: UInt32) Required

Creates a new value, rounded to the closest possible representation.

If two representable values are equally close, the result is the value with more trailing zeros in its significand bit pattern.

`value`: The integer to convert to a floating-point value.

Declaration

`init(_ value: UInt32)`
init(_: UInt64) Required

Creates a new value, rounded to the closest possible representation.

If two representable values are equally close, the result is the value with more trailing zeros in its significand bit pattern.

`value`: The integer to convert to a floating-point value.

Declaration

`init(_ value: UInt64)`
init(sign:exponent:significand:) Required

Creates a new value from the given sign, exponent, and significand.

The following example uses this initializer to create a new `Double` instance. `Double` is a binary floating-point type that has a radix of `2`.

``````let x = Double(sign: .plus, exponent: -2, significand: 1.5)
// x == 0.375``````

This initializer is equivalent to the following calculation, where `**` is exponentiation, computed as if by a single, correctly rounded, floating-point operation:

``````let sign: FloatingPointSign = .plus
let exponent = -2
let significand = 1.5
let y = (sign == .minus ? -1 : 1) * significand * Double.radix ** exponent
// y == 0.375``````

As with any basic operation, if this value is outside the representable range of the type, overflow or underflow occurs, and zero, a subnormal value, or infinity may result. In addition, there are two other edge cases:

• If the value you pass to `significand` is zero or infinite, the result is zero or infinite, regardless of the value of `exponent`.
• If the value you pass to `significand` is NaN, the result is NaN.

For any floating-point value `x` of type `F`, the result of the following is equal to `x`, with the distinction that the result is canonicalized if `x` is in a noncanonical encoding:

``let x0 = F(sign: x.sign, exponent: x.exponent, significand: x.significand)``

This initializer implements the `scaleB` operation defined by the IEEE 754 specification.

Parameters: sign: The sign to use for the new value. exponent: The new value's exponent. significand: The new value's significand.

Declaration

`init(sign: FloatingPointSign, exponent: Self.Exponent, significand: Self)`
init(signOf:magnitudeOf:) Required

Creates a new floating-point value using the sign of one value and the magnitude of another.

The following example uses this initializer to create a new `Double` instance with the sign of `a` and the magnitude of `b`:

``````let a = -21.5
let b = 305.15
let c = Double(signOf: a, magnitudeOf: b)
print(c)
// Prints "-305.15"``````

This initializer implements the IEEE 754 `copysign` operation.

Parameters: signOf: A value from which to use the sign. The result of the initializer has the same sign as `signOf`. magnitudeOf: A value from which to use the magnitude. The result of the initializer has the same magnitude as `magnitudeOf`.

Declaration

`init(signOf: Self, magnitudeOf: Self)`
init(integerLiteral:)

Creates an instance initialized to the specified integer value.

Do not call this initializer directly. Instead, initialize a variable or constant using an integer literal. For example:

``let x = 23``

In this example, the assignment to the `x` constant calls this integer literal initializer behind the scenes.

`value`: The value to create.

Declaration

`init(integerLiteral value: Self.IntegerLiteralType)`

Declared In

`ExpressibleByIntegerLiteral`

Static Variables

static var greatestFiniteMagnitude: Self Required

The greatest finite number representable by this type.

This value compares greater than or equal to all finite numbers, but less than `infinity`.

This value corresponds to type-specific C macros such as `FLT_MAX` and `DBL_MAX`. The naming of those macros is slightly misleading, because `infinity` is greater than this value.

Declaration

`static var greatestFiniteMagnitude: Self { get }`
static var infinity: Self Required

Positive infinity.

Infinity compares greater than all finite numbers and equal to other infinite values.

``````let x = Double.greatestFiniteMagnitude
let y = x * 2
// y == Double.infinity
// y > x``````

Declaration

`static var infinity: Self { get }`
static var leastNonzeroMagnitude: Self Required

The least positive number.

This value compares less than or equal to all positive numbers, but greater than zero. If the type supports subnormal values, `leastNonzeroMagnitude` is smaller than `leastNormalMagnitude`; otherwise they are equal.

Declaration

`static var leastNonzeroMagnitude: Self { get }`
static var leastNormalMagnitude: Self Required

The least positive normal number.

This value compares less than or equal to all positive normal numbers. There may be smaller positive numbers, but they are subnormal, meaning that they are represented with less precision than normal numbers.

This value corresponds to type-specific C macros such as `FLT_MIN` and `DBL_MIN`. The naming of those macros is slightly misleading, because subnormals, zeros, and negative numbers are smaller than this value.

Declaration

`static var leastNormalMagnitude: Self { get }`
static var nan: Self Required

A quiet NaN ("not a number").

A NaN compares not equal, not greater than, and not less than every value, including itself. Passing a NaN to an operation generally results in NaN.

``````let x = 1.21
// x > Double.nan == false
// x < Double.nan == false
// x == Double.nan == false``````

Because a NaN always compares not equal to itself, to test whether a floating-point value is NaN, use its `isNaN` property instead of the equal-to operator (`==`). In the following example, `y` is NaN.

``````let y = x + Double.nan
print(y == Double.nan)
// Prints "false"
print(y.isNaN)
// Prints "true"``````

See Also: `isNaN`, `signalingNaN`

Declaration

`static var nan: Self { get }`
static var pi: Self Required

The mathematical constant pi.

This value should be rounded toward zero to keep user computations with angles from inadvertently ending up in the wrong quadrant. A type that conforms to the `FloatingPoint` protocol provides the value for `pi` at its best possible precision.

``````print(Double.pi)
// Prints "3.14159265358979"``````

Declaration

`static var pi: Self { get }`

The radix, or base of exponentiation, for a floating-point type.

The magnitude of a floating-point value `x` of type `F` can be calculated by using the following formula, where `**` is exponentiation:

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

A conforming type may use any integer radix, but values other than 2 (for binary floating-point types) or 10 (for decimal floating-point types) are extraordinarily rare in practice.

Declaration

`static var radix: Int { get }`
static var signalingNaN: Self Required

A signaling NaN ("not a number").

The default IEEE 754 behavior of operations involving a signaling NaN is to raise the Invalid flag in the floating-point environment and return a quiet NaN.

Operations on types conforming to the `FloatingPoint` protocol should support this behavior, but they might also support other options. For example, it would be reasonable to implement alternative operations in which operating on a signaling NaN triggers a runtime error or results in a diagnostic for debugging purposes. Types that implement alternative behaviors for a signaling NaN must document the departure.

Other than these signaling operations, a signaling NaN behaves in the same manner as a quiet NaN.

See Also: `nan`

Declaration

`static var signalingNaN: Self { get }`
static var ulpOfOne: Self

The unit in the last place of 1.0.

The positive difference between 1.0 and the next greater representable number. The `ulpOfOne` constant corresponds to the C macros `FLT_EPSILON`, `DBL_EPSILON`, and others with a similar purpose.

Declaration

`static var ulpOfOne: Self { get }`

Instance Variables

var exponent: Self.Exponent Required

The exponent of the floating-point value.

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

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.

Declaration

`var exponent: Self.Exponent { get }`
var floatingPointClass: FloatingPointClassification

The classification of this value.

A value's `floatingPointClass` property describes its "class" as described by the IEEE 754 specification.

Declaration

`var floatingPointClass: FloatingPointClassification { get }`
var isCanonical: Bool Required

A Boolean value indicating whether the instance's representation is in the canonical form.

The IEEE 754 specification defines a canonical, or preferred, encoding of a floating-point value's representation. Every `Float` or `Double` value is canonical, but noncanonical values of the `Float80` type exist, and noncanonical values may exist for other types that conform to the `FloatingPoint` protocol.

Declaration

`var isCanonical: Bool { get }`
var isFinite: Bool Required

A Boolean value indicating whether this instance is finite.

All values other than NaN and infinity are considered finite, whether normal or subnormal.

Declaration

`var isFinite: Bool { get }`
var isInfinite: Bool Required

A Boolean value indicating whether the instance is infinite.

Note that `isFinite` and `isInfinite` do not form a dichotomy, because they are not total: If `x` is `NaN`, then both properties are `false`.

Declaration

`var isInfinite: Bool { get }`
var isNaN: Bool Required

A Boolean value indicating whether the instance is NaN ("not a number").

Because NaN is not equal to any value, including NaN, use this property instead of the equal-to operator (`==`) or not-equal-to operator (`!=`) to test whether a value is or is not NaN. For example:

``````let x = 0.0
let y = x * .infinity
// y is a NaN

// Comparing with the equal-to operator never returns 'true'
print(x == Double.nan)
// Prints "false"
print(y == Double.nan)
// Prints "false"

// Test with the 'isNaN' property instead
print(x.isNaN)
// Prints "false"
print(y.isNaN)
// Prints "true"``````

This property is `true` for both quiet and signaling NaNs.

Declaration

`var isNaN: Bool { get }`
var isNormal: Bool Required

A Boolean value indicating whether this instance is normal.

A normal value is a finite number that uses the full precision available to values of a type. Zero is neither a normal nor a subnormal number.

Declaration

`var isNormal: Bool { get }`
var isSignalingNaN: Bool Required

A Boolean value indicating whether the instance is a signaling NaN.

Signaling NaNs typically raise the Invalid flag when used in general computing operations.

Declaration

`var isSignalingNaN: Bool { get }`
var isSubnormal: Bool Required

A Boolean value indicating whether the instance is subnormal.

A subnormal value is a nonzero number that has a lesser magnitude than the smallest normal number. Subnormal values do not use the full precision available to values of a type.

Zero is neither a normal nor a subnormal number. Subnormal numbers are often called denormal or denormalized---these are different names for the same concept.

Declaration

`var isSubnormal: Bool { get }`
var isZero: Bool Required

A Boolean value indicating whether the instance is equal to zero.

The `isZero` property of a value `x` is `true` when `x` represents either `-0.0` or `+0.0`. `x.isZero` is equivalent to the following comparison: `x == 0.0`.

``````let x = -0.0
x.isZero        // true
x == 0.0        // true``````

Declaration

`var isZero: Bool { get }`
var nextDown: Self

The greatest representable value that compares less than this value.

For any finite value `x`, `x.nextDown` is greater than `x`. For `nan` or `-infinity`, `x.nextDown` is `x` itself. The following special cases also apply:

• If `x` is `infinity`, then `x.nextDown` is `greatestFiniteMagnitude`.
• If `x` is `leastNonzeroMagnitude`, then `x.nextDown` is `0.0`.
• If `x` is zero, then `x.nextDown` is `-leastNonzeroMagnitude`.
• If `x` is `-greatestFiniteMagnitude`, then `x.nextDown` is `-infinity`.

Declaration

`var nextDown: Self { get }`
var nextUp: Self Required

The least representable value that compares greater than this value.

For any finite value `x`, `x.nextUp` is greater than `x`. For `nan` or `infinity`, `x.nextUp` is `x` itself. The following special cases also apply:

• If `x` is `-infinity`, then `x.nextUp` is `-greatestFiniteMagnitude`.
• If `x` is `-leastNonzeroMagnitude`, then `x.nextUp` is `-0.0`.
• If `x` is zero, then `x.nextUp` is `leastNonzeroMagnitude`.
• If `x` is `greatestFiniteMagnitude`, then `x.nextUp` is `infinity`.

Declaration

`var nextUp: Self { get }`
var sign: FloatingPointSign Required

The sign of the floating-point value.

The `sign` property is `.minus` if the value's signbit is set, and `.plus` otherwise. For example:

``````let x = -33.375
// x.sign == .minus``````

Do not use this property to check whether a floating point value is negative. For a value `x`, the comparison `x.sign == .minus` is not necessarily the same as `x < 0`. In particular, `x.sign == .minus` if `x` is -0, and while `x < 0` is always `false` if `x` is NaN, `x.sign` could be either `.plus` or `.minus`.

Declaration

`var sign: FloatingPointSign { get }`
var significand: Self Required

The significand of the floating-point value.

The magnitude of a floating-point value `x` of type `F` can be calculated by using the following formula, 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

If a type's radix is 2, then for finite nonzero numbers, the significand is in the range `1.0 ..< 2.0`. For other values of `x`, `x.significand` is defined as follows:

• If `x` is zero, then `x.significand` is 0.0.
• If `x` is infinity, then `x.significand` is 1.0.
• If `x` is NaN, then `x.significand` is NaN. Note: The significand is frequently also called the mantissa, but significand is the preferred terminology in the IEEE 754 specification, to allay confusion with the use of mantissa for the fractional part of a logarithm.

Declaration

`var significand: Self { get }`
var ulp: Self Required

The unit in the last place of this value.

This is the unit of the least significant digit in this value's significand. For most numbers `x`, this is the difference between `x` and the next greater (in magnitude) representable number. There are some edge cases to be aware of:

• If `x` is not a finite number, then `x.ulp` is NaN.
• If `x` is very small in magnitude, then `x.ulp` may be a subnormal number. If a type does not support subnormals, `x.ulp` may be rounded to zero.
• `greatestFiniteMagnitude.ulp` is a finite number, even though the next greater representable value is `infinity`.

This quantity, or a related quantity, is sometimes called epsilon or machine epsilon. Avoid that name because it has different meanings in different languages, which can lead to confusion, and because it suggests that it is a good tolerance to use for comparisons, which it almost never is.

Declaration

`var ulp: Self { get }`
var magnitude: Self.Magnitude Required

Declaration

`var magnitude: Self.Magnitude { get }`

Declared In

`Arithmetic`

Static Methods

static func abs(_:) Required

Returns the absolute value of `x`.

Declaration

`static func abs(_ x: Self) -> Self`

Declared In

`AbsoluteValuable`
static func maximum(_:_:)

Returns the greater of the two given values.

This method returns the maximum of two values, preserving order and eliminating NaN when possible. For two values `x` and `y`, the result of `maximum(x, y)` is `x` if `x > y`, `y` if `x <= y`, or whichever of `x` or `y` is a number if the other is a quiet NaN. If both `x` and `y` are NaN, or either `x` or `y` is a signaling NaN, the result is NaN.

``````Double.maximum(10.0, -25.0)
// 10.0
Double.maximum(10.0, .nan)
// 10.0
Double.maximum(.nan, -25.0)
// -25.0
Double.maximum(.nan, .nan)
// nan``````

The `maximum` method implements the `maxNum` operation defined by the IEEE 754 specification.

Parameters: x: A floating-point value. y: Another floating-point value. Returns: The greater of `x` and `y`, or whichever is a number if the other is NaN.

Declaration

`static func maximum(_ x: Self, _ y: Self) -> Self`
static func maximumMagnitude(_:_:)

Returns the value with greater magnitude.

This method returns the value with greater magnitude of the two given values, preserving order and eliminating NaN when possible. For two values `x` and `y`, the result of `maximumMagnitude(x, y)` is `x` if `x.magnitude > y.magnitude`, `y` if `x.magnitude <= y.magnitude`, or whichever of `x` or `y` is a number if the other is a quiet NaN. If both `x` and `y` are NaN, or either `x` or `y` is a signaling NaN, the result is NaN.

``````Double.maximumMagnitude(10.0, -25.0)
// -25.0
Double.maximumMagnitude(10.0, .nan)
// 10.0
Double.maximumMagnitude(.nan, -25.0)
// -25.0
Double.maximumMagnitude(.nan, .nan)
// nan``````

The `maximumMagnitude` method implements the `maxNumMag` operation defined by the IEEE 754 specification.

Parameters: x: A floating-point value. y: Another floating-point value. Returns: Whichever of `x` or `y` has greater magnitude, or whichever is a number if the other is NaN.

Declaration

`static func maximumMagnitude(_ x: Self, _ y: Self) -> Self`
static func minimum(_:_:)

Returns the lesser of the two given values.

This method returns the minimum of two values, preserving order and eliminating NaN when possible. For two values `x` and `y`, the result of `minimum(x, y)` is `x` if `x <= y`, `y` if `y < x`, or whichever of `x` or `y` is a number if the other is a quiet NaN. If both `x` and `y` are NaN, or either `x` or `y` is a signaling NaN, the result is NaN.

``````Double.minimum(10.0, -25.0)
// -25.0
Double.minimum(10.0, .nan)
// 10.0
Double.minimum(.nan, -25.0)
// -25.0
Double.minimum(.nan, .nan)
// nan``````

The `minimum` method implements the `minNum` operation defined by the IEEE 754 specification.

Parameters: x: A floating-point value. y: Another floating-point value. Returns: The minimum of `x` and `y`, or whichever is a number if the other is NaN.

Declaration

`static func minimum(_ x: Self, _ y: Self) -> Self`
static func minimumMagnitude(_:_:)

Returns the value with lesser magnitude.

This method returns the value with lesser magnitude of the two given values, preserving order and eliminating NaN when possible. For two values `x` and `y`, the result of `minimumMagnitude(x, y)` is `x` if `x.magnitude <= y.magnitude`, `y` if `y.magnitude < x.magnitude`, or whichever of `x` or `y` is a number if the other is a quiet NaN. If both `x` and `y` are NaN, or either `x` or `y` is a signaling NaN, the result is NaN.

``````Double.minimumMagnitude(10.0, -25.0)
// 10.0
Double.minimumMagnitude(10.0, .nan)
// 10.0
Double.minimumMagnitude(.nan, -25.0)
// -25.0
Double.minimumMagnitude(.nan, .nan)
// nan``````

The `minimumMagnitude` method implements the `minNumMag` operation defined by the IEEE 754 specification.

Parameters: x: A floating-point value. y: Another floating-point value. Returns: Whichever of `x` or `y` has lesser magnitude, or whichever is a number if the other is NaN.

Declaration

`static func minimumMagnitude(_ x: Self, _ y: Self) -> Self`

Instance Methods

func <(_:rhs:) Required

Returns a Boolean value indicating whether the value of the first argument is less than that of the second argument.

This function is the only requirement of the `Comparable` protocol. The remainder of the relational operator functions are implemented by the standard library for any type that conforms to `Comparable`.

Parameters: lhs: A value to compare. rhs: Another value to compare.

Declaration

`func <(lhs: Self, rhs: Self) -> Bool`

Declared In

`Comparable`
func <=(_:rhs:)

Returns a Boolean value indicating whether the value of the first argument is less than or equal to that of the second argument.

Parameters: lhs: A value to compare. rhs: Another value to compare.

Declaration

`func <=(lhs: Self, rhs: Self) -> Bool`

Declared In

`Comparable`
func ==(_:rhs:) Required

Returns a Boolean value indicating whether two values are equal.

Equality is the inverse of inequality. For any values `a` and `b`, `a == b` implies that `a != b` is `false`.

Parameters: lhs: A value to compare. rhs: Another value to compare.

Declaration

`func ==(lhs: Self, rhs: Self) -> Bool`

Declared In

`Equatable`
func >(_:rhs:)

Returns a Boolean value indicating whether the value of the first argument is greater than that of the second argument.

Parameters: lhs: A value to compare. rhs: Another value to compare.

Declaration

`func >(lhs: Self, rhs: Self) -> Bool`

Declared In

`Comparable`
func >=(_:rhs:)

Returns a Boolean value indicating whether the value of the first argument is greater than or equal to that of the second argument.

Parameters: lhs: A value to compare. rhs: Another value to compare.

Declaration

`func >=(lhs: Self, rhs: Self) -> Bool`

Declared In

`Comparable`
prefix func -(_:) Required

Returns the result of negating `x`.

Declaration

`prefix func -(x: Self) -> Self`

Declared In

`SignedNumber`
func -(_:rhs:) Required

Returns the difference between `lhs` and `rhs`.

Declaration

`func -(lhs: Self, rhs: Self) -> Self`

Declared In

`SignedNumber`

Adds the given value to this value in place, rounded to a representable value.

This method serves as the basis for the in-place addition operator (`+=`). For example:

``````var (x, y) = (2.25, 2.25)
// x == 9.25
y += 7.0
// y == 9.25``````

`other`: The value to add.

See Also: `adding(_:)`

Declaration

`mutating func add(_ other: Self)`

Declared In

`FloatingPoint`, `Arithmetic`

Adds the product of the two given values to this value in place, computed without intermediate rounding.

Parameters: lhs: One of the values to multiply before adding to this value. rhs: The other value to multiply.

Declaration

`mutating func addProduct(_ lhs: Self, _ rhs: Self)`

Returns the sum of this value and the given value, rounded to a representable value.

This method serves as the basis for the addition operator (`+`). For example:

``````let x = 1.5
// Prints "3.75"
print(x + 2.25)
// Prints "3.75"``````

The `adding(_:)` method implements the addition operation defined by the IEEE 754 specification.

`other`: The value to add. Returns: The sum of this value and `other`, rounded to a representable value.

See Also: `add(_:)`

Declaration

`func adding(_ other: Self) -> Self`

Declared In

`FloatingPoint`, `Arithmetic`

Returns the result of adding the product of the two given values to this value, computed without intermediate rounding.

This method is equivalent to the C `fma` function and implements the `fusedMultiplyAdd` operation defined by the IEEE 754 specification.

Parameters: lhs: One of the values to multiply before adding to this value. rhs: The other value to multiply. Returns: The product of `lhs` and `rhs`, added to this value.

Declaration

`func addingProduct(_ lhs: Self, _ rhs: Self) -> Self`

Returns a `Self` `x` such that `self.distance(to: x)` approximates `n`.

If `Stride` conforms to `Integer`, then `self.distance(to: x) == n`.

Complexity: O(1).

Declaration

`func advanced(by n: Self.Stride) -> Self`

Declared In

`Strideable`
func distance(to:) Required

Returns a stride `x` such that `self.advanced(by: x)` approximates `other`.

If `Stride` conforms to `Integer`, then `self.advanced(by: x) == other`.

Complexity: O(1).

Declaration

`func distance(to other: Self) -> Self.Stride`

Declared In

`Strideable`
mutating func divide(by:) Required

Divides this value by the given value in place, rounding to a representable value.

This method serves as the basis for the in-place division operator (`/=`). For example:

``````var (x, y) = (16.875, 16.875)
x.divide(by: 2.25)
// x == 7.5
y /= 2.25
// y == 7.5``````

`other`: The value to use when dividing this value.

See Also: `divided(by:)`

Declaration

`mutating func divide(by other: Self)`

Declared In

`FloatingPoint`, `Arithmetic`
func divided(by:)

Returns the quotient of this value and the given value, rounded to a representable value.

This method serves as the basis for the division operator (`/`). For example:

``````let x = 7.5
let y = x.divided(by: 2.25)
// y == 16.875
let z = x * 2.25
// z == 16.875``````

The `divided(by:)` method implements the division operation defined by the IEEE 754 specification.

`other`: The value to use when dividing this value. Returns: The quotient of this value and `other`, rounded to a representable value.

See Also: `divide(by:)`

Declaration

`func divided(by other: Self) -> Self`

Declared In

`FloatingPoint`, `Arithmetic`
mutating func formRemainder(dividingBy:) Required

Replaces this value with the remainder of itself divided by the given value.

For two finite values `x` and `y`, the remainder `r` of dividing `x` by `y` satisfies `x == y * q + r`, where `q` is the integer nearest to `x / y`. If `x / y` is exactly halfway between two integers, `q` is chosen to be even. Note that `q` is not `x / y` computed in floating-point arithmetic, and that `q` may not be representable in any available integer type.

The following example calculates the remainder of dividing 8.625 by 0.75:

``````var x = 8.625
print(x / 0.75)
// Prints "11.5"

let q = (x / 0.75).rounded(.toNearestOrEven)
// q == 12.0
x.formRemainder(dividingBy: 0.75)
// x == -0.375

let x1 = 0.75 * q + x
// x1 == 8.625``````

If this value and `other` are finite numbers, the remainder is in the closed range `-abs(other / 2)...abs(other / 2)`. The `remainder(dividingBy:)` method is always exact.

`other`: The value to use when dividing this value.

See Also: `remainder(dividingBy:)`, `formTruncatingRemainder(dividingBy:)`

Declaration

`mutating func formRemainder(dividingBy other: Self)`
mutating func formSquareRoot() Required

Replaces this value with its square root, rounded to a representable value.

See Also: `sqrt(_:)`, `squareRoot()`

Declaration

`mutating func formSquareRoot()`
mutating func formTruncatingRemainder(dividingBy:) Required

Replaces this value with the remainder of itself divided by the given value using truncating division.

Performing truncating division with floating-point values results in a truncated integer quotient and a remainder. For values `x` and `y` and their truncated integer quotient `q`, the remainder `r` satisfies `x == y * q + r`.

The following example calculates the truncating remainder of dividing 8.625 by 0.75:

``````var x = 8.625
print(x / 0.75)
// Prints "11.5"

let q = (x / 0.75).rounded(.towardZero)
// q == 11.0
x.formTruncatingRemainder(dividingBy: 0.75)
// x == 0.375

let x1 = 0.75 * q + x
// x1 == 8.625``````

If this value and `other` are both finite numbers, the truncating remainder has the same sign as this value and is strictly smaller in magnitude than `other`. The `formTruncatingRemainder(dividingBy:)` method is always exact.

`other`: The value to use when dividing this value.

See Also: `truncatingRemainder(dividingBy:)`, `formRemainder(dividingBy:)`

Declaration

`mutating func formTruncatingRemainder(dividingBy other: Self)`
func isEqual(to:) Required

Returns a Boolean value indicating whether this instance is equal to the given value.

This method serves as the basis for the equal-to operator (`==`) for floating-point values. When comparing two values with this method, `-0` is equal to `+0`. NaN is not equal to any value, including itself. For example:

``````let x = 15.0
x.isEqual(to: 15.0)
// true
x.isEqual(to: .nan)
// false
Double.nan.isEqual(to: .nan)
// false``````

The `isEqual(to:)` method implements the equality predicate defined by the IEEE 754 specification.

`other`: The value to compare with this value. Returns: `true` if `other` has the same value as this instance; otherwise, `false`.

Declaration

`func isEqual(to other: Self) -> Bool`
func isLess(than:) Required

Returns a Boolean value indicating whether this instance is less than the given value.

This method serves as the basis for the less-than operator (`<`) for floating-point values. Some special cases apply:

• Because NaN compares not less than nor greater than any value, this method returns `false` when called on NaN or when NaN is passed as `other`.
• `-infinity` compares less than all values except for itself and NaN.
• Every value except for NaN and `+infinity` compares less than `+infinity`.

let x = 15.0 x.isLess(than: 20.0) // true x.isLess(than: .nan) // false Double.nan.isLess(than: x) // false

The `isLess(than:)` method implements the less-than predicate defined by the IEEE 754 specification.

`other`: The value to compare with this value. Returns: `true` if `other` is less than this value; otherwise, `false`.

Declaration

`func isLess(than other: Self) -> Bool`
func isLessThanOrEqualTo(_:) Required

Returns a Boolean value indicating whether this instance is less than or equal to the given value.

This method serves as the basis for the less-than-or-equal-to operator (`<=`) for floating-point values. Some special cases apply:

• Because NaN is incomparable with any value, this method returns `false` when called on NaN or when NaN is passed as `other`.
• `-infinity` compares less than or equal to all values except NaN.
• Every value except NaN compares less than or equal to `+infinity`.

let x = 15.0 x.isLessThanOrEqualTo(20.0) // true x.isLessThanOrEqualTo(.nan) // false Double.nan.isLessThanOrEqualTo(x) // false

The `isLessThanOrEqualTo(_:)` method implements the less-than-or-equal predicate defined by the IEEE 754 specification.

`other`: The value to compare with this value. Returns: `true` if `other` is less than this value; otherwise, `false`.

Declaration

`func isLessThanOrEqualTo(_ other: Self) -> Bool`
func isTotallyOrdered(belowOrEqualTo:) Required

Returns a Boolean value indicating whether this instance should precede the given value in an ascending sort.

This relation is a refinement of the less-than-or-equal-to operator (`<=`) that provides a total order on all values of the type, including noncanonical encodings, signed zeros, and NaNs. Because it is used much less frequently than the usual comparisons, there is no operator form of this relation.

The following example uses `isTotallyOrdered(below:)` to sort an array of floating-point values, including some that are NaN:

``````var numbers = [2.5, 21.25, 3.0, .nan, -9.5]
numbers.sort { \$0.isTotallyOrdered(below: \$1) }
// numbers == [-9.5, 2.5, 3.0, 21.25, nan]``````

The `isTotallyOrdered(belowOrEqualTo:)` method implements the total order relation as defined by the IEEE 754 specification.

`other`: A floating-point value to compare to this value. Returns: `true` if this value is ordered below `other` in a total ordering of the floating-point type; otherwise, `false`.

Declaration

`func isTotallyOrdered(belowOrEqualTo other: Self) -> Bool`
func multiplied(by:)

Returns the product of this value and the given value, rounded to a representable value.

This method serves as the basis for the multiplication operator (`*`). For example:

``````let x = 7.5
print(x.multiplied(by: 2.25))
// Prints "16.875"
print(x * 2.25)
// Prints "16.875"``````

The `multiplied(by:)` method implements the multiplication operation defined by the IEEE 754 specification.

`other`: The value to multiply by this value. Returns: The product of this value and `other`, rounded to a representable value.

See Also: `multiply(by:)`

Declaration

`func multiplied(by other: Self) -> Self`

Declared In

`FloatingPoint`, `Arithmetic`
mutating func multiply(by:) Required

Multiplies this value by the given value in place, rounding to a representable value.

This method serves as the basis for the in-place multiplication operator (`*=`). For example:

``````var (x, y) = (7.5, 7.5)
x.multiply(by: 2.25)
// x == 16.875
y *= 2.25
// y == 16.875``````

`other`: The value to multiply by this value.

See Also: `multiplied(by:)`

Declaration

`mutating func multiply(by other: Self)`

Declared In

`FloatingPoint`, `Arithmetic`
mutating func negate() Required

Replaces this value with its additive inverse.

The result is always exact. This example uses the `negate()` method to negate the value of the variable `x`:

``````var x = 21.5
x.negate()
// x == -21.5``````

See Also: `negated()`

Declaration

`mutating func negate()`
func negated()

Returns the additive inverse of this value.

The result is always exact. This method serves as the basis for the negation operator (prefixed `-`). For example:

``````let x = 21.5
let y = x.negated()
// y == -21.5``````

Returns: The additive inverse of this value.

See Also: `negate()`

Declaration

`func negated() -> Self`
func remainder(dividingBy:)

Returns the remainder of this value divided by the given value.

For two finite values `x` and `y`, the remainder `r` of dividing `x` by `y` satisfies `x == y * q + r`, where `q` is the integer nearest to `x / y`. If `x / y` is exactly halfway between two integers, `q` is chosen to be even. Note that `q` is not `x / y` computed in floating-point arithmetic, and that `q` may not be representable in any available integer type.

The following example calculates the remainder of dividing 8.625 by 0.75:

``````let x = 8.625
print(x / 0.75)
// Prints "11.5"

let q = (x / 0.75).rounded(.toNearestOrEven)
// q == 12.0
let r = x.remainder(dividingBy: 0.75)
// r == -0.375

let x1 = 0.75 * q + r
// x1 == 8.625``````

If this value and `other` are finite numbers, the remainder is in the closed range `-abs(other / 2)...abs(other / 2)`. The `remainder(dividingBy:)` method is always exact. This method implements the remainder operation defined by the IEEE 754 specification.

`other`: The value to use when dividing this value. Returns: The remainder of this value divided by `other`.

See Also: `formRemainder(dividingBy:)`, `truncatingRemainder(dividingBy:)`

Declaration

`func remainder(dividingBy other: Self) -> Self`
mutating func round(_:) Required

Rounds the value to an integral value using the specified rounding rule.

The following example rounds a value using four different rounding rules:

``````// Equivalent to the C 'round' function:
var w = 6.5
w.round(.toNearestOrAwayFromZero)
// w == 7.0

// Equivalent to the C 'trunc' function:
var x = 6.5
x.round(.towardZero)
// x == 6.0

// Equivalent to the C 'ceil' function:
var y = 6.5
y.round(.up)
// y == 7.0

// Equivalent to the C 'floor' function:
var z = 6.5
z.round(.down)
// z == 6.0``````

For more information about the available rounding rules, see the `FloatingPointRoundingRule` enumeration. To round a value using the default "schoolbook rounding", you can use the shorter `round()` method instead.

``````var w1 = 6.5
w1.round()
// w1 == 7.0``````

`rule`: The rounding rule to use.

See Also: `round()`, `rounded(_:)`, `FloatingPointRoundingRule`

Declaration

`mutating func round(_ rule: FloatingPointRoundingRule)`
func rounded(_:)

Returns this value rounded to an integral value using the specified rounding rule.

The following example rounds a value using four different rounding rules:

``````let x = 6.5

// Equivalent to the C 'round' function:
print(x.rounded(.toNearestOrAwayFromZero))
// Prints "7.0"

// Equivalent to the C 'trunc' function:
print(x.rounded(.towardZero))
// Prints "6.0"

// Equivalent to the C 'ceil' function:
print(x.rounded(.up))
// Prints "7.0"

// Equivalent to the C 'floor' function:
print(x.rounded(.down))
// Prints "6.0"``````

For more information about the available rounding rules, see the `FloatingPointRoundingRule` enumeration. To round a value using the default "schoolbook rounding", you can use the shorter `rounded()` method instead.

``````print(x.rounded())
// Prints "7.0"``````

`rule`: The rounding rule to use. Returns: The integral value found by rounding using `rule`.

See Also: `rounded()`, `round(_:)`, `FloatingPointRoundingRule`

Declaration

`func rounded(_ rule: FloatingPointRoundingRule) -> Self`
func squareRoot()

Returns the square root of the value, rounded to a representable value.

The following example declares a function that calculates the length of the hypotenuse of a right triangle given its two perpendicular sides.

``````func hypotenuse(_ a: Double, _ b: Double) -> Double {
return (a * a + b * b).squareRoot()
}

let (dx, dy) = (3.0, 4.0)
let distance = hypotenuse(dx, dy)
// distance == 5.0``````

Returns: The square root of the value.

See Also: `sqrt(_:)`, `formSquareRoot()`

Declaration

`func squareRoot() -> Self`
mutating func subtract(_:) Required

Subtracts the given value from this value in place, rounding to a representable value.

This method serves as the basis for the in-place subtraction operator (`-=`). For example:

``````var (x, y) = (7.5, 7.5)
x.subtract(2.25)
// x == 5.25
y -= 2.25
// y == 5.25``````

`other`: The value to subtract.

See Also: `subtracting(_:)`

Declaration

`mutating func subtract(_ other: Self)`

Declared In

`FloatingPoint`, `Arithmetic`
func subtracting(_:)

Returns the difference of this value and the given value, rounded to a representable value.

This method serves as the basis for the subtraction operator (`-`). For example:

``````let x = 7.5
print(x.subtracting(2.25))
// Prints "5.25"
print(x - 2.25)
// Prints "5.25"``````

The `subtracting(_:)` method implements the subtraction operation defined by the IEEE 754 specification.

`other`: The value to subtract from this value. Returns: The difference of this value and `other`, rounded to a representable value.

See Also: `subtract(_:)`

Declaration

`func subtracting(_ other: Self) -> Self`

Declared In

`FloatingPoint`, `Arithmetic`
func truncatingRemainder(dividingBy:)

Returns the remainder of this value divided by the given value using truncating division.

Performing truncating division with floating-point values results in a truncated integer quotient and a remainder. For values `x` and `y` and their truncated integer quotient `q`, the remainder `r` satisfies `x == y * q + r`.

The following example calculates the truncating remainder of dividing 8.625 by 0.75:

``````let x = 8.625
print(x / 0.75)
// Prints "11.5"

let q = (x / 0.75).rounded(.towardZero)
// q == 11.0
let r = x.truncatingRemainder(dividingBy: 0.75)
// r == 0.375

let x1 = 0.75 * q + r
// x1 == 8.625``````

If this value and `other` are both finite numbers, the truncating remainder has the same sign as this value and is strictly smaller in magnitude than `other`. The `truncatingRemainder(dividingBy:)` method is always exact.

`other`: The value to use when dividing this value. Returns: The remainder of this value divided by `other` using truncating division.

See Also: `formTruncatingRemainder(dividingBy:)`, `remainder(dividingBy:)`

Declaration

`func truncatingRemainder(dividingBy other: Self) -> Self`

Default Implementations

init()

`init()`

Declared In

`Arithmetic`
init(integerLiteral:)

Create an instance initialized to `value`.

Declaration

`init(integerLiteral value: Self)`

Declared In

`Arithmetic` , `AbsoluteValuable` , `ExpressibleByIntegerLiteral`
static var ulpOfOne: Self

Declaration

`static var ulpOfOne: Self { get }`
var floatingPointClass: FloatingPointClassification

Declaration

`var floatingPointClass: FloatingPointClassification { get }`
var nextDown: Self

Declaration

`var nextDown: Self { get }`

Declaration

`func adding(_ other: Self) -> Self`

Declared In

`FloatingPoint`, `Arithmetic`

Declaration

`func addingProduct(_ lhs: Self, _ rhs: Self) -> Self`
func divided(by:)

Declaration

`func divided(by other: Self) -> Self`

Declared In

`FloatingPoint`, `Arithmetic`
static func maximum(_:_:)

Declaration

`static func maximum(_ x: Self, _ y: Self) -> Self`
static func maximumMagnitude(_:_:)

Declaration

`static func maximumMagnitude(_ x: Self, _ y: Self) -> Self`
static func minimum(_:_:)

Declaration

`static func minimum(_ x: Self, _ y: Self) -> Self`
static func minimumMagnitude(_:_:)

Declaration

`static func minimumMagnitude(_ x: Self, _ y: Self) -> Self`
func multiplied(by:)

Declaration

`func multiplied(by other: Self) -> Self`

Declared In

`FloatingPoint`, `Arithmetic`
func negated()

Declaration

`func negated() -> Self`
func remainder(dividingBy:)

Declaration

`func remainder(dividingBy rhs: Self) -> Self`
mutating func round()

Rounds this value to an integral value using "schoolbook rounding."

The `round()` method uses the `.toNearestOrAwayFromZero` rounding rule, where a value halfway between two integral values is rounded to the one with greater magnitude. The following example rounds several values using this default rule:

``````var x = 5.2
x.round()
// x == 5.0
var y = 5.5
y.round()
// y == 6.0
var z = -5.5
z.round()
// z == -6.0``````

To specify an alternative rule for rounding, use the `round(_:)` method instead.

See Also: `round(_:)`, `rounded()`, `FloatingPointRoundingRule`

Declaration

`mutating func round()`
func rounded()

Returns this value rounded to an integral value using "schoolbook rounding."

The `rounded()` method uses the `.toNearestOrAwayFromZero` rounding rule, where a value halfway between two integral values is rounded to the one with greater magnitude. The following example rounds several values using this default rule:

``````(5.2).rounded()
// 5.0
(5.5).rounded()
// 6.0
(-5.2).rounded()
// -5.0
(-5.5).rounded()
// -6.0``````

To specify an alternative rule for rounding, use the `rounded(_:)` method instead.

Returns: The nearest integral value, or, if two integral values are equally close, the integral value with greater magnitude.

See Also: `rounded(_:)`, `round()`, `FloatingPointRoundingRule`

Declaration

`func rounded() -> Self`
func rounded(_:)

Declaration

`func rounded(_ rule: FloatingPointRoundingRule) -> Self`
func squareRoot()

Declaration

`func squareRoot() -> Self`
func subtracting(_:)

Declaration

`func subtracting(_ other: Self) -> Self`

Declared In

`FloatingPoint`, `Arithmetic`
func truncatingRemainder(dividingBy:)

Declaration

`func truncatingRemainder(dividingBy other: Self) -> Self`