---
title: "formStereoRamp(withInitialValue:multiplyingBy:_:increment:results:_:)"
framework: accelerate
role: symbol
role_heading: Type Method
path: "accelerate/vdsp/formstereoramp(withinitialvalue:multiplyingby:_:increment:results:_:)-99lyb"
---

# formStereoRamp(withInitialValue:multiplyingBy:_:increment:results:_:)

Populates two single-precision vectors that contain stereo monotonically incrementing or decrementing values multiplied by two source vectors.

## Declaration

```swift
static func formStereoRamp<U, V>(withInitialValue initialValue: inout Double, multiplyingBy multiplierOne: U, _ multiplierTwo: U, increment: Double, results resultOne: inout V, _ resultTwo: inout V) where U : AccelerateBuffer, V : AccelerateMutableBuffer, U.Element == Double, V.Element == Double
```

## 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.
- `resultOne`: The array to overwrite with the first generated ramp.
- `resultTwo`: The array to overwrite with the second generated ramp.

## Discussion

Discussion Use this function to populate 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: let n = vDSP_Length(1024)

let multiplierOne: [Double] = (0 ..< n).map {     return sin(Double($0) / 20) * 2 }

let multiplierTwo: [Double] = (0 ..< n).map {     return sin(Double($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 formStereoRamp(withInitialValue:multiplyingBy:_:increment:results:_:): var start: Double = 0 let step: Double = 0.1

var resultOne = [Double](repeating: 0,                          count: Int(n)) var resultTwo = [Double](repeating: 0,                          count: Int(n))

vDSP.formStereoRamp(withInitialValue: &start,                     multiplyingBy: multiplierOne, multiplierTwo,                     increment: step,                     results: &resultOne, &resultTwo) 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:

## See Also

### Type Methods

- [absolute(_:)](accelerate/vdsp/absolute(_:)-9c3ge.md)
- [absolute(_:)](accelerate/vdsp/absolute(_:)-5ehc1.md)
- [absolute(_:result:)](accelerate/vdsp/absolute(_:result:)-9x5jn.md)
- [absolute(_:result:)](accelerate/vdsp/absolute(_:result:)-1wu9x.md)
- [absolute(_:result:)](accelerate/vdsp/absolute(_:result:)-657bd.md)
- [absolute(_:result:)](accelerate/vdsp/absolute(_:result:)-4pigo.md)
- [add(_:_:)](accelerate/vdsp/add(_:_:)-9mv1a.md)
- [add(_:_:)](accelerate/vdsp/add(_:_:)-2ftxc.md)
- [add(_:_:)](accelerate/vdsp/add(_:_:)-53nh9.md)
- [add(_:_:)](accelerate/vdsp/add(_:_:)-7swvf.md)
- [add(_:_:result:)](accelerate/vdsp/add(_:_:result:)-2531u.md)
- [add(_:_:result:)](accelerate/vdsp/add(_:_:result:)-2w0o9.md)
- [add(_:_:result:)](accelerate/vdsp/add(_:_:result:)-338hl.md)
- [add(_:_:result:)](accelerate/vdsp/add(_:_:result:)-3vzwi.md)
- [add(_:to:count:result:)](accelerate/vdsp/add(_:to:count:result:)-g1dk.md)