vDSP_vmmsbD

Declaration

extern void vDSP_vmmsbD(const double *__A, vDSP_Stride __IA, const double *__B, vDSP_Stride __IB, const double *__C, vDSP_Stride __IC, const double *__D, vDSP_Stride __ID, double *__E, vDSP_Stride __IE, vDSP_Length __N);

Parameters

• __A:

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

• __IA:

  The distance between the elements in the input vector A.

• __B:

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

• __IB:

  The distance between the elements in the input vector B.

• __C:

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

• __IC:

  The distance between the elements in the input vector C.

• __D:

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

• __ID:

  The distance between the elements in the input vector D.

• __E:

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

• __IE:

  The distance between the elements in the output vector E.

• __N:

  The number of elements that the function processes.

Discussion

This function calculates the differences of the first N elements of the product of vectors A and B and the product of vectors C and D.

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

[Image]

The following code shows an example of using this function:

    let stride = 1
    let count = 5
    
    let a: [Double] = [ 1,  2,  3,  4,  5]
    let b: [Double] = [10, 20, 30, 40, 50]
    let c: [Double] = [ 5,  4,  3,  2,  1]
    let d: [Double] = [50, 40, 30, 20, 10]
    
    let e = [Double](unsafeUninitializedCapacity: count) {
        buffer, initializedCount in
        
        vDSP_vmmsbD(a, stride,
                    b, stride,
                    c, stride,
                    d, stride,
                    buffer.baseAddress!, stride,
                    vDSP_Length(count))
        
        initializedCount = count
    }
    
    // Prints "[-240.0, -120.0, 0.0, 120.0, 240.0]".
    print(e)

See Also

Quaternary multiply-multiply-subtract operations

• vDSP_vmmsb