# stereoRamp(withInitialValue:multiplyingBy:_:increment:) Returns two single-precision vectors that contain stereo monotonically incrementing or decrementing values multiplied by two source vectors. ``` static func stereoRamp(withInitialValue initialValue: inout Float, multiplyingBy multiplierOne: U, _ multiplierTwo: U, increment: Float) -> (firstOutput: [Float], secondOutput: [Float]) where U : AccelerateBuffer, U.Element == Float ``` ## Parameters `initialValue` The initial value of the ramp. `multiplierOne` The first input vector that’s multiplied by the ramp function. `multiplierTwo` The second input vector that’s multiplied by the ramp function. `increment` The increment, or decrement if negative, between each generated element. ## Discussion Use this function to create two vectors by multiplying the values in two input vectors with the corresponding values of a ramp. For example, the following code fills the arrays `multiplierOne` and `multiplierTwo` with sine values: ```swift let n = vDSP_Length(1024) let multiplierOne: [Float] = (0 ..< n).map { return sin(Float($0) / 20) * 2 } let multiplierTwo: [Float] = (0 ..< n).map { return sin(Float($0) / 40) } ``` The following figure illustrates the values of `multiplierOne`, as a solid line, and `multiplierTwo`, as a dashed line:  Pass `multiplierOne` and `multiplierTwo` as the `multiplyingBy` parameter of [`stereoRamp(withInitialValue:multiplyingBy:_:increment:)`](/documentation/Accelerate/vDSP/stereoRamp(withInitialValue:multiplyingBy:_:increment:)-18f8z): ```swift var start: Float = 0 let step: Float = 0.1 let results = vDSP.stereoRamp(withInitialValue: &start, multiplyingBy: multiplierOne, multiplierTwo, increment: step) ``` On return, the output vectors, `results.firstOutput` and `results.secondOutput`, contain ramped-sine waves. The figure below shows the first output as a solid line and the second output as a dashed line:  --- 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)