Advanced numeric data types for Swift 4, including BigInt, Rational, and Complex numbers.
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Swift NumberKit

Platform: macOS Language: Swift 4.2 IDE: Xcode 10.0 License: Apache


This is a framework implementing advanced numeric data types for the Swift 4 programming language. The current version provides three new numeric types:

  1. BigInt: arbitrary-precision signed integers
  2. Rational: signed rational numbers
  3. Complex: complex floating-point numbers


  • Xcode 10.0
  • Swift 4.2
  • macOS with Xcode or Swift Package Manager
  • Linux with Swift Package Manager

Note: So far, with every major version of Swift, Apple decided to change the foundational APIs of the numeric types in Swift significantly and consistently in a backward incompatible way. In order to be more isolated from such changes in future, I decided to introduce a distinct integer type used in NumberKit using a new protocol IntegerNumber. All standard numeric integer types implement this protocol. This is now consistent with the usage of protocol FloatingPointNumber for floating point numbers, where there was, so far, never a good, generic enough foundation (and still isn't). Unfortunately, this is a change that might break some client usage of NumberKit. Adaptations should be straightforward.


BigInt objects are immutable, signed, arbitrary-precision integers that can be used as a drop-in replacement for the existing binary integer types of Swift 4. Struct BigInt defines all the standard arithmetic integer operations and implements the corresponding protocols defined in the standard library.


Struct Rational<T> defines immutable, rational numbers based on an existing signed integer type T, like Int32, Int64, or BigInt. A rational number is a signed number that can be expressed as the quotient of two integers a and b: a / b.


Struct Complex<T> defines complex numbers based on an existing floating point type T, like Float or Double. A complex number consists of two components, a real part re and an imaginary part im and is typically written as: re + im * i where i is the imaginary unit.