MATLAB svd(x) in Swift

SVD.swift

//
//  SVD.swift
//
//  Created by Dongwan Kim on 2015. 10. 30..
//

/* MATLAB svd(X)

For the matrix

    X =
        1    2
        3    4
        5    6
        7    8

the statement

    [U,S,V] = svd(X)

produces

    U =
        -0.1525   -0.8226   -0.3945   -0.3800
        -0.3499   -0.4214    0.2428    0.8007
        -0.5474   -0.0201    0.6979   -0.4614
        -0.7448    0.3812   -0.5462    0.0407

    S =
        14.2691         0
              0    0.6268
              0         0
              0         0

    V =
        -0.6414     0.7672
        -0.7672    -0.6414
*/

import Foundation
import Accelerate

func testSVD() {
    let x = [1.0, 3.0, 5.0, 7.0, 2.0, 4.0, 6.0, 8.0]
    let m = 4
    let n = 2
    var u : [Double]
    var s : [Double]
    var v : [Double]
    (u, s, v) = svd(x, m: m, n: n)
    print(u)
    print(s)
    print(v)
}

func svd(x:[Double], m:Int, n:Int) -> (u:[Double], s:[Double], v:[Double]) {
    var JOBZ = Int8(UnicodeScalar("A").value)
    var M = __CLPK_integer(m)
    var N = __CLPK_integer(n)
    var A = x
    var LDA = __CLPK_integer(m)
    var S = [__CLPK_doublereal](count: min(m,n), repeatedValue: 0.0)
    var U = [__CLPK_doublereal](count: m*m, repeatedValue: 0.0)
    var LDU = __CLPK_integer(m)
    var VT = [__CLPK_doublereal](count: n*n, repeatedValue: 0.0)
    var LDVT = __CLPK_integer(n)
    let lwork = min(m,n)*(6+4*min(m,n))+max(m,n)
    var WORK = [__CLPK_doublereal](count: lwork, repeatedValue: 0.0)
    var LWORK = __CLPK_integer(lwork)
    var IWORK = [__CLPK_integer](count: 8*min(m,n), repeatedValue: 0)
    var INFO = __CLPK_integer(0)
    dgesdd_(&JOBZ, &M, &N, &A, &LDA, &S, &U, &LDU, &VT, &LDVT, &WORK, &LWORK, &IWORK, &INFO)
    var s = [Double](count: m*n, repeatedValue: 0.0)
    for ni in 0...n-1 {
        s[ni*m+ni] = S[ni]
    }
    var v = [Double](count: n*n, repeatedValue: 0.0)
    vDSP_mtransD(VT, 1, &v, 1, vDSP_Length(n), vDSP_Length(n))
    return (U, s, v)
}

Thankyou !!!🤗