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我正在尝试解决数学公式中的三个变量。公式如下：

Dim secondMomentOfBeam As Func(Of Beamμ2params, Double, Double) =
    Function(params, z)
        Return params.σ0 ^ 2 + (params.M2 ^ 2) * Math.Pow(λ / (Math.PI * params.σ0), 2) * Math.Pow(z - params.z0, 2)
    End Function

使用

Friend Class Beamμ2params
    Public σ0 As Double
    Public z0 As Double
    Public M2 As Double

    Public Sub New(ByVal sigmaNot As Double, ByVal zNot As Double, ByVal Msquared As Double)
        Me.σ0 = sigmaNot
        Me.z0 = zNot
        Me.M2 = Msquared
    End Sub
End Class

我需要创建一个循环来抖动每个变量 σ0、z0 和 M2，然后检查整体误差平方，然后根据误差平方重复或完成。

While errorSquared > 1
    ' minimize error with σ0 
    ' minimize error with z0 
    ' minimize error with M2 
End While

我不想为每个变量硬编码这个循环（并且有很多相同的代码块），我更喜欢有一个函数可以最小化任何变量，这取决于选择变量的 lambda，像这样调用

Dim minimizeErrorSquared As Func(Of Beamμ2params, Func(Of Beamμ2params, Double), Double, UInt32, Beamμ2params) =
    Function(params, selector, dither, iterations)
        ' dither value chosen by selector
        ' check error-squared
        ' dither toward zero
        ' up to max iterations
    End Function

使用selector第二个参数，选择将抖动的变量。这使我的循环现在看起来像

Dim params As New Beamμ2params(σ0initial, z0initial, M2initial)
While errorSquared > 1
    params = minimizeErrorSquared(params, Function(p As Beamμ2params) p.σ0, 0.01, 10)
    params = minimizeErrorSquared(params, Function(p As Beamμ2params) p.z0, 5, 10)
    params = minimizeErrorSquared(params, Function(p As Beamμ2params) p.M2, 0.05, 10)
    ' calculate error squared based on raw data and params
End While

我无法解决的问题是如何将新变量值应用于内部的适当变量minimizeErrorSquared，然后返回更改了新变量的参数。我尝试了一个带ByRef参数的委托（这里没有什么值得粘贴的），但不能完全将新变量值传递回主循环。我正在寻找有关如何在概念上完成我的思路的建议，或者有人从不同的角度提出建议并提出不同的范式。

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1 回答 1

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这是一个解决方案，但我不想要。理想情况下，三个 Func 应该写成一个 Func。寻找更好的解决方案

Dim minimizeErrorSquaredσ0 As Func(Of Beamμ2params, Double, UInt32, Beamμ2params) =
    Function(params, dither, iterations)
        ' minimize error-squared using params.σ0
    End Function

Dim minimizeErrorSquaredz0 As Func(Of Beamμ2params, Double, UInt32, Beamμ2params) =
    Function(params, dither, iterations)
        ' minimize error-squared using params.z0
    End Function

Dim minimizeErrorSquaredM2 As Func(Of Beamμ2params, Double, UInt32, Beamμ2params) =
    Function(params, dither, iterations)
        ' minimize error-squared using params.M2
    End Function

Try
    Dim errorSquared As Double = Double.MaxValue
    Dim params As New Beamμ2params(σ0initial, z0initial, M2initial)
    While errorSquared > 1
        params = minimizeErrorSquaredσ0(params, 0.01, 10)
        params = minimizeErrorSquaredz0(params, 5, 10)
        params = minimizeErrorSquaredM2(params, 0.1, 10)
        ' calculate error squared based on raw data and params
    End While
    Finally
End Try
于 2013-03-21T19:02:10.020 回答