vDSP_vdistD

Declaration

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

Parameters

• __A:

  A vector that contains the lengths of the first set of legs of the triangles.

• __IA:

  The distance between the elements in the input vector A.

• __B:

  A vector that contains the lengths of the second set of legs of the triangles.

• __IB:

  The distance between the elements in the input vector B.

• __C:

  The output vector.

• __IC:

  The distance between the elements in the output vector C.

• __N:

  The number of elements to process.

Discussion

The vDSP_vdist and vDSP_vdistD functions calculate the square roots of the sum of the squares of corresponding elements of vectors A and B, using the following operation:

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

For example, the following code calculates the hypotenuse of four Pythagorean triples:

let a: [Float] = [3, 6, 5, 9]
let b: [Float] = [4, 8, 12, 12]

var c: [Float] = [0, 0, 0, 0]

let stride = vDSP_Stride(1)

vDSP_vdist(a, stride,
           b, stride,
           &c, stride,
           vDSP_Length(c.count))

On return, c contains [5.0, 10.0, 13.0, 15.0].

See Also

Vector distance computation

• vDSP_vdist
• vDSP_distancesq
• vDSP_distancesqD