Matrix math in Swift using Accelerate framework

gistfile1.swift

import Accelerate

struct Matrix4 {
    var m11: Float
    var m12: Float
    var m13: Float
    var m14: Float
    var m21: Float
    var m22: Float
    var m23: Float
    var m24: Float
    var m31: Float
    var m32: Float
    var m33: Float
    var m34: Float
    var m41: Float
    var m42: Float
    var m43: Float
    var m44: Float
}

func *(var lhs: Matrix4, var rhs: Matrix4) -> Matrix4 {
    
    var result = Matrix4.Identity
    withUnsafePointer(&lhs) { ptr -> Void in
        let a = unsafeBitCast(ptr, UnsafePointer<Float>.self)
        withUnsafePointer(&rhs) { ptr -> Void in
            let b = unsafeBitCast(ptr, UnsafePointer<Float>.self)
            withUnsafePointer(&result) { ptr -> Void in
                let c = unsafeBitCast(ptr, UnsafeMutablePointer<Float>.self)
                vDSP_mmul(a, 1, b, 1, c, 1, 4, 4, 4)
            }
        }
    }
    return result
}