# subtract(multiplication:_:result:) Calculates the single-precision element-wise difference of the product of a vector and a scalar value, and a vector. ``` static func subtract(multiplication: (a: U, b: Float), _ vector: T, result: inout V) where T : AccelerateBuffer, U : AccelerateBuffer, V : AccelerateMutableBuffer, T.Element == Float, U.Element == Float, V.Element == Float ``` ## Parameters `multiplication` A tuple that contains the vectors `A` and `B` in `D = (A * B) - C`. `vector` The input scalar value `C` in `D = (A * B) - C`. `result` The output vector `D` in `D = (A * B) - C`. ## Discussion This function calculates the element-wise product of vector `A` and scalar value `B`, subtracts vector `C` from the product, and writes the result to vector `D`. ```swift for (n = 0; n < N; ++n) D[n] = A[n] * B - C[n]; ``` ![A diagram showing the operation of this function. There are four rows. The top row represents the input vector A with three boxes, and the scalar value B with one box. The second row represents the operation that multiplies A and B, with three boxes, as well as the input vector C with three boxes. The third row represents the subtraction operation as three boxes. The bottom row represents the output vector D as three boxes. The diagram has connecting lines from the input vectors to the operations, and from the operations to the output vector. ](images/com.apple.accelerate/media-4387395@2x.png) The following code shows an example of using this function: ```swift let count = 5 let a: [Float] = [ 1, 2, 3, 4, 5] let b: Float = 10 let c: [Float] = [ 5, 4, 3, 2, 1] let d = [Float](unsafeUninitializedCapacity: count) { buffer, initializedCount in vDSP.subtract(multiplication: (a, b), c, result: &buffer) initializedCount = count } // Prints "[5.0, 16.0, 27.0, 38.0, 49.0]". print(d) ``` --- 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)