linal - Linear Algebra library for Pony Language

Tuple-based Linear Algebra for typical 2D, 3D operations

• operate on the stack
• 100% immutable
• side-effect free functions
• float32 internals (F32)
• 🐎 pure pony
• efficient wrapper classes available for convenience

Status

• v0.2.0 - 2018-03-03
• v0.1.0 - 2018-02-19

Applicability

This library is intended for use in common 2D and 3D applications not as a scientific or precise mathematics library. Various scientific libraries such as LAPACK, GSL or others can be bound with the Pony C ABI.

Installation

• Install pony-stable
• Update your bundle.json

{ 
  "type": "github",
  "repo": "dougmacdoug/ponylang-linal"
}

• stable fetch to fetch your dependencies
• use "linal" to include this package
• stable env ponyc to compile your application

Type System

Each TYPE consists of a type alias, a primitive, and a wrapper class

• A type alias to a tuple (similar to class state data)
• A primitive function collection (similar to methods)
• the first argument is similar to "this" except it is immutable
• rather than modify state, result is returned as immutable stack tuple
• optional wrapper class
• wrapper class methods only produce tuples to prevent unwanted instantiation
• wrapper classes accept both tuples and instances for convenience

Example for Vector 2

• V2 => Type Alias for tuple (F32, F32)
• V2fun => primitive function collection that acts on and returns V2 tuples
• Vector2 => wrapper class for convenience, embedding, and persistent handle

  let a = (F32(1), F32(1)) // simple tuple compatible with V2

  let b: V2 = (3, 3)       // declared type alias forces 3's to F32
  let c = V2fun(3, 3)      // apply sugar => V2
  let d = V2fun.add(a, b)  // a + b
  let f = V2fun.mul(V2fun.unit(d), 5) // normalize d and scale to 5 units

  let v2 = Linear.vector2()   // readable function alias to V2fun
  let p1 = v2(1, 2)           // alias + apply sugar
  let p2 = v2.add(p1, (1, 1)) // p2 = p1 + (1, 1)

  let vec = Vector2 // wrapper class
  vec() = vec + p1  // vec = vec + p1 via add sugar, update sugar
  vec() = vec * 5   // vec = vec * 5 via mul sugar, update sugar
  vec(p2)           // vec = p2 via apply sugar

  // wrapper classes accept other wrapper instances or tuples
  let other1 = Vector2(vec)
  let other2 = Vector2(p1)
  // functions with results do not generate GC'd classes, only tuples
  let result: V2 = other1 + other2
  // update sugar looks closer to traditional linear classes
  other1() = other1 + other2

Types

Type	Func	Wrapper	Tuple
V2	V2fun	Vector2	(x: F32, y: F32)
V3	V3fun	Vector3	(x: F32, y: F32, z: F32)
V4	V4fun	Vector4	(x: F32, y: F32, z: F32, w: F32)
M2	M2fun	Matrix2	(x: V2, y: V2)
M3	M3fun	Matrix3	(x: V3, y: V3, z: V3)
M4	M4fun	Matrix4	(x: V4, y: V4, z: V4, w: V4)
Q4	Q4fun	Quaternion	(x: V4, y: V4, z: V4, w: V4)
R4	R4fun	Rect	(origin: V2, width: F32, height: F32)
R2	R2fun	Ray	(position: V3, direction: V3)
P4	P4fun	Plane	(normal: V3, distance: F32)

Utility

• Linear - various linal utility functions
• Intersect - hit test functions

@TODO // MAYBEDO

• docstring references
• unit test coverage
• examples
• slerp nlerp
• faster Q4
• add fast sqrt for length operations
• consider writing longhand (dist2 = distance_squared)
• try to use compile time expressions once adopted by pony fun inv(q: Q4): Q4 => #(div(conj(q), dot(q, q)))