# formRamp(withInitialValue:multiplyingBy:increment:result:) Populates a double-precision vector that contains monotonically incrementing or decrementing values, and multiplies that vector by a source vector. ``` static func formRamp(withInitialValue initialValue: inout Double, multiplyingBy vector: U, increment: Double, result: inout V) where U : AccelerateBuffer, V : AccelerateMutableBuffer, U.Element == Double, V.Element == Double ``` ## Parameters `initialValue` On input, the initial value of the ramp. On output, the next value in the ramp. `vector` The input vector that the function multiplies by the ramp. `increment` The increment, or decrement if negative, between each generated element. `result` The result. ## Discussion Use this function to generate and return a vector populated with ramped values with each element multiplied by the corresponding element in a second vector. The following code generates a ramped vector with values in the range `0 ... 7`. The function multiplies elements at even indices by `10` and multiplies elements at odd indices by `100`. ```swift let n = 8 var initialValue: Double = 0 let increment: Double = 1 let ramp = [Double](unsafeUninitializedCapacity: n) { buffer, initializedCount in vDSP.formRamp(withInitialValue: &initialValue, multiplyingBy: [10, 100, 10, 100, 10, 100, 10, 100], increment: increment, result: &buffer) initializedCount = n } // Prints "[0.0, 100.0, 20.0, 300.0, 40.0, 500.0, 60.0, 700.0]". print(ramp) // Prints "8". print(initialValue) ``` --- 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)