# vDSP_zdotpr Calculates the dot product of two single-precision complex vectors. ``` extern void vDSP_zdotpr(const DSPSplitComplex *__A, vDSP_Stride __IA, const DSPSplitComplex *__B, vDSP_Stride __IB, const DSPSplitComplex *__C, vDSP_Length __N); ``` ## Parameters `__A` The input vector `A`. `__IA` The distance between the elements in the input vector `A`. `__B` The input vector `B`. `__IB` The distance between the elements in the input vector `B`. `__C` On output, the dot product of the two vectors. `__N` The number of elements to process. ## Discussion This function calculates the dot product of two vectors, using the following operation: ```objc C[0] = sum(A[n] * B[n], 0 <= n < N); ``` For example, the following code calculates the dot product of the two vectors `[1, 2, 3]` and `[4, 5, 6]` as `(1*4)+(2*5)+(3*6)=32`: ```swift let stride = 1 let n = 3 let aReal = UnsafeMutableBufferPointer.allocate(capacity: n) _ = aReal.initialize(from: [ 1.0, 2.0, 3.0 ]) let aImag = UnsafeMutableBufferPointer.allocate(capacity: n) _ = aImag.initialize(from: [ 0.0, 0.0, 0.0 ]) var a = DSPSplitComplex(realp: aReal.baseAddress!, imagp: aImag.baseAddress!) let bReal = UnsafeMutableBufferPointer.allocate(capacity: n) _ = bReal.initialize(from: [ 4.0, 5.0, 6.0 ]) let bImag = UnsafeMutableBufferPointer.allocate(capacity: n) _ = bImag.initialize(from: [ 0.0, 0.0, 0.0 ]) var b = DSPSplitComplex(realp: bReal.baseAddress!, imagp: bImag.baseAddress!) let cReal = UnsafeMutablePointer.allocate(capacity: 1) let cImag = UnsafeMutablePointer.allocate(capacity: 1) var c = DSPSplitComplex(realp: cReal, imagp: cImag) vDSP_zdotpr(&a, stride, &b, stride, &c, vDSP_Length(n)) // Prints "32.0 0.0". print(cReal.pointee, cImag.pointee) ``` --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)