Using Accelerate framework in Swift

Question

From the apple docs

According to the docs

    func vvlog10f(_ _: UnsafeMutablePointer<Float>,
                _ _: UnsafePointer<Float>,
                _ _: UnsafePointer<Int32>)
 /* y */ /* x */ /* n */

So what am I doing wrong?

Here's my code

import Accelerate

var input:[Float] = [0.124,0.5,0.0056]
var output:[Float] = []
var i:Int32 = Int32(input.count)
vvlog10f(&output,&input,&i)

println("output is \(output)")

The output is []

Answer 1

Example from Apple's Swift Blog :

   import Accelerate

   let a: [Float] = [1, 2, 3, 4]
   let b: [Float] = [0.5, 0.25, 0.125, 0.0625]
   var result: [Float] = [0, 0, 0, 0]

   vDSP_vadd(a, 1, b, 1, &result, 1, 4)

So it seems you only need the & for the mutable pointer.

Answer 2

This is what finally worked for this example

import Accelerate

var input:[Float] = [0.124,0.5,0.0006]
var output:[Float] = [Float](count: input.count, repeatedValue: 0.0)
var temp:Int32 = Int32(input.count)
var i:[Int32] = [temp]
vvlog10f(&output,input,i)

println("output is \(output)")