Function

vDSP_zvsub(_:_:_:_:_:_:_:)

Subtracts two single-precision complex vectors.

Declaration

func vDSP_zvsub(_ __A: UnsafePointer<DSPSplitComplex>, _ __IA: vDSP_Stride, _ __B: UnsafePointer<DSPSplitComplex>, _ __IB: vDSP_Stride, _ __C: UnsafePointer<DSPSplitComplex>, _ __IC: vDSP_Stride, _ __N: vDSP_Length)

Parameters

__A

Single-precision complex input vector.

__IA

Stride for A.

__B

Single-precision complex input vector.

__IB

Stride for B.

__C

Single-precision complex output vector.

__IC

Stride for C.

__N

The number of elements to process.

Discussion

This function calculates the differences of the first N complex elements of A and B, writing the result to C:

A diagram showing the operation of the vDSP_zvsub function. There are three rows. The top row represents the first input, vector A. The second row represents the second input, vector B. The bottom row represents the output, vector C. The diagram has connecting lines from the input vectors to the output vector indicating the relationships between the inputs and output.

The operation is:

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

The following code shows an example of using vDSP_zvsub(_:_:_:_:_:_:_:):

let n = vDSP_Length(4)
let stride = vDSP_Stride(1)

var realA: [Float] = [100, 200, 300, 400]
var realB: [Float] = [10, 20, 30, 40]

var imagA: [Float] = [10, 20, 30, 40]
var imagB: [Float] = [4, 3, 2, 1]

var a = [DSPSplitComplex(realp: &realA,
                         imagp: &imagA)]

var b = [DSPSplitComplex(realp: &realB,
                         imagp: &imagB)]

var realC = [Float](repeating: .nan,
                    count: Int(n))
var imagC = [Float](repeating: .nan,
                    count: Int(n))
var c = DSPSplitComplex(realp: &realC,
                        imagp: &imagC)

vDSP_zvsub(&a, stride,
           &b, stride,
           &c, stride,
           n)

print("real", realC) // Prints "real [90.0, 180.0, 270.0, 360.0]"
print("imag", imagC) // Prints "imag [6.0, 17.0, 28.0, 39.0]"

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