vDSP_rmsqv

Declaration

void vDSP_rmsqv(const float *__A, vDSP_Stride __IA, float *__C, vDSP_Length __N);

Parameters

• __A:

  The single-precision real input vector A.

• __I:

  The stride for input vector A.

• __C:

  The single-precision output scalar.

• __N:

  The number of elements to process. If N is zero (0), this function returns NAN.

Discussion

This function calculates the root mean square of the first N elements of A and writes the result to C:

[Image]

The operation is:

C = sqrt(sum(A[n] ** 2, 0 <= n < N) / N);

The following code shows an example of using vDSP_rmsqv:

let stride = vDSP_Stride(1)

let a: [Float] = [-1.5, 2.25, 3.6,
                  0.2, -0.1, -4.3]
let n = vDSP_Length(a.count)

var c: Float = .nan

vDSP_rmsqv(a,
           stride,
           &c,
           n)

print(String(format: "RMS %.4f", c)) // Prints "RMS 2.5434".

See Also

Vector Reduction Functions

• vDSP_svesq
• vDSP_svs