Contents

multiply(subtraction:_:result:)

Calculates the double-precision element-wise product of the difference of two vectors and a scalar value.

Declaration

static func multiply<T, U, V>(subtraction: (a: T, b: U), _ scalar: Double, result: inout V) where T : AccelerateBuffer, U : AccelerateBuffer, V : AccelerateMutableBuffer, T.Element == Double, U.Element == Double, V.Element == Double

Parameters

  • subtraction:

    A tuple that contains the vectors A and B in D = (A - B) * C.

  • scalar:

    The input scalar value C in D = (A - B) * C.

  • result:

    The output vector D in D = (A - B) * C.

Discussion

This function calculates the element-wise difference of vectors A and B, multiplies the difference by scalar value C, and writes the result to vector D.

 for (n = 0; n < N; ++n)
    D[n] = (A[n] - B[n]) * C;

[Image]

The following code shows an example of using this function:

    let count = 5
    
    let a: [Double] = [ 1,  2,  3,  4,  5]
    let b: [Double] = [10, 20, 30, 40, 50]
    let c: Double = 5
    
    let d = [Double](unsafeUninitializedCapacity: count) {
        buffer, initializedCount in
        
        vDSP.multiply(subtraction: (a, b), 
                      c,
                      result: &buffer)
        
        initializedCount = count
    }
    
    // Prints "[-45.0, -90.0, -135.0, -180.0, -225.0]".
    print(d)

See Also

Multiplication