Contents

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

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

Declaration

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

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:

[Image]

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:

[Image]

See Also

Type Methods