vDSP_vmaD

Declaration

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

Parameters

• __A:

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

• __IA:

  The distance between the elements in the input vector A.

• __B:

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

• __IB:

  The distance between the elements in the input vector B.

• __C:

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

• __IC:

  The distance between the elements in the input vector C.

• __D:

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

• __ID:

  The distance between the elements in the output vector D.

• __N:

  The number of elements that the function processes.

Discussion

This function calculates the products of the first N elements of A and B, adds each product to the corresponding value in C, and writes the result to D.

 for (n = 0; n < N; ++n)
    D[n] = (A[n] * B[n]) + C[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](unsafeUninitializedCapacity: count) {
        buffer, initializedCount in
        
        vDSP_vmaD(a, stride,
                  b, stride,
                  c, stride,
                  buffer.baseAddress!, stride,
                  vDSP_Length(count))
        
        initializedCount = count
    }
    
    // Prints "[15.0, 44.0, 93.0, 162.0, 251.0]".
    print(d)

See Also

Ternary multiply-add operations

• vDSP_vma