1
我試過但是當我鍵入這些翻譯對Cordic wikipedia webpage斯威夫特CORDIC算法給定答案
的MATLAB語言:
print(cordic(beta: Double.pi/9, n: 20))
print(cordic(beta: Double.pi/8, n: 20))
我得到
[-0.17163433840184755, 0.98516072489744066]
[-0.17163433840184755, 0.98516072489744066]
它總是給我一個常數回答。爲什麼?我確定「角度」和「Kvalues」數組是正確計算的。
下面的代碼:
import Foundation
var angles: [Double] = []
for i: Double in stride(from: 0, to: 27, by: 1) {
angles.append(atan(pow(2, -i)))
}
var Kvalues: [Double] = []
for i: Double in stride(from: 0, to: 23, by: 1) {
Kvalues.append(1/sqrt(abs(Double(1) + pow(2,-2 * i))))
if i > 0 {
Kvalues[Kvalues.count - 1] *= Kvalues[Kvalues.count - 2]
}
}
func min(_ a: Int, _ b: Int) -> Int {
return a > b ? b : a
}
func cordic(beta: Double, n: Int) -> [Double] {
var beta1 = beta
let Kn = Kvalues[min(n, Kvalues.count - 1)]
var v: [Double] = [1,0]
var poweroftwo: Double = 1
var angle = angles[0]
for j in 0 ..< n {
let sigma: Double = beta < 0 ? -1 : 1
let factor: Double = sigma * poweroftwo
v = [v[0] - v[1] * factor, v[1] + v[0] * factor]
beta1 -= sigma * angle
poweroftwo /= 2
angle = j + 2 > angles.count ? angle/2 : angles[j + 2]
}
return [v[0] * Kn, v[1] * Kn]
}
print(cordic(beta: Double.pi/9, n: 20))
print(cordic(beta: Double.pi/8, n: 20))