有人知道如何在vb.net中制作正态分布的随机数吗？
谢谢
GaussNumDist(Mean, Standard Deviation, Sample Size)
下面的代码示例，该示例将使用数字样本填充GaussNumArray()，其样本的分布将指定均值和标准差：
Imports System.Math
Module Module1
Friend GaussNumArray() As Double
Friend intICell As Long
Friend Function GaussNumDist(ByVal Mean As Double, ByVal StdDev As Double, ByVal SampleSize As Integer)
intICell = 1 'Loop variable
ReDim GaussNumArray(SampleSize)
Do While (intICell < (SampleSize + 1))
Call NumDist(Mean, StdDev)
Application.DoEvents()
Loop
End Function
Sub NumDist(ByVal meanin As Double, ByVal sdin As Double)
'---------------------------------------------------------------------------------
'Converts uniform random numbers over the region 0 to 1 into Gaussian distributed
'random numbers using Box-Muller algorithm.
'Adapted from Numerical Recipes in C
'---------------------------------------------------------------------------------
'Defining variables
Dim dblR1 As Double
Dim dblR2 As Double
Dim mean As Double
Dim var As Double
Dim circ As Double
Dim trans As Double
Dim dblY1 As Double
Dim dblY2 As Double
Dim Pi As Double
Pi = 4 * Atan(1)
'Get two random numbers
dblR1 = (2 * UniformRandomNumber()) - 1
dblR2 = (2 * UniformRandomNumber()) - 1
circ = (dblR1 ^ 2) + (dblR2 ^ 2) 'Radius of circle
If circ >= 1 Then 'If outside unit circle, then reject number
Call NumDist(meanin, sdin)
Exit Sub
End If
'Transform to Gaussian
trans = Sqrt(-2 * Log(circ) / circ)
dblY1 = (trans * dblR1 * sdin) + meanin
dblY2 = (trans * dblR2 * sdin) + meanin
GaussNumArray(intICell) = dblY1 'First number
'Increase intICell for next random number
intICell = (intICell + 1)
GaussNumArray(intICell) = dblY2 'Second number
'Increase intICell again ready for next call of ConvertNumberDistribution
intICell = (intICell + 1)
End Sub
Friend Function UniformRandomNumber() As Double
'-----------------------------------------------------------------------------------
'Outputs random numbers with a period of > 2x10^18 in the range 0 to 1 (exclusive)
'Implements a L'Ecuyer generator with Bays-Durham shuffle
'Adapted from Numerical Recipes in C
'-----------------------------------------------------------------------------------
'Defining constants
Const IM1 As Double = 2147483563
Const IM2 As Double = 2147483399
Const AM As Double = (1.0# / IM1)
Const IMM1 As Double = (IM1 - 1.0#)
Const IA1 As Double = 40014
Const IA2 As Double = 40692
Const IQ1 As Double = 53668
Const IQ2 As Double = 52774
Const IR1 As Double = 12211
Const IR2 As Double = 3791
Const NTAB As Double = 32
Const NDIV As Double = (1.0# + IM1 / NTAB)
Const ESP As Double = 0.00000012
Const RNMX As Double = (1.0# - ESP)
Dim iCell As Integer
Dim idum As Double
Dim j As Integer
Dim k As Long
Dim temp As Double
Static idum2 As Long
Static iy As Long
Static iv(NTAB) As Long
idum2 = 123456789
iy = 0
'Seed value required is a negative integer (idum)
Randomize()
idum = (-Rnd() * 1000)
'For loop to generate a sequence of random numbers based on idum
For iCell = 1 To 10
'Initialize generator
If (idum <= 0) Then
'Prevent idum = 0
If (-(idum) < 1) Then
idum = 1
Else
idum = -(idum)
End If
idum2 = idum
For j = (NTAB + 7) To 0
k = ((idum) / IQ1)
idum = ((IA1 * (idum - (k * IQ1))) - (k * IR1))
If (idum < 0) Then
idum = (idum + IM1)
End If
If (j < NTAB) Then
iv(j) = idum
End If
Next j
iy = iv(0)
End If
'Start here when not initializing
k = (idum / IQ1)
idum = ((IA1 * (idum - (k * IQ1))) - (k * IR1))
If (idum < 0) Then
idum = (idum + IM1)
End If
k = (idum2 / IQ2)
idum2 = ((IA2 * (idum2 - (k * IQ2))) - (k * IR2))
If (idum2 < 0) Then
idum2 = idum2 + IM2
End If
j = (iy / NDIV)
iy = (iv(j) - idum2)
iv(j) = idum
If (iy < 1) Then
iy = (iy + IMM1)
End If
temp = AM * iy
If (temp <= RNMX) Then
'Return the value of the random number
UniformRandomNumber = temp
End If
Next iCell
End Function
End Module
Dim x1 as Double = MathNet.Numerics.Distributions.Normal.Sample(MEAN, STDEV)
可以使用以下NuGet命令安装Math.Net Numeric软件包
Install-Package MathNet.Numerics -Version 4.9.0
您可以在NuGet site上找到更多信息