how to generate random numbers that follow skew normal distribution in matlab
I have probability de开发者_开发技巧nsity function of skew normal distribution.I want to generate random number that follow the skew normal distribution in matlab.
Can't vouch for their performance/adequacy, but http://azzalini.stat.unipd.it/SN/ says the following, and has a link to a .zip file of MATLAB functions:
The library has been ported to Matlab by Nicola Sartori. So far, this refers to update 0.21; hence facilities for the skew-t distribution are not included. A portion of the facilities for the skew-t distribution is however available via a set of Matlab functions which have been written and made available by Enrique Batiz (Enrique.Batiz [at] postgrad.mbs.ac.uk)
Also see this code which is in visual Basic, but should be easily portable. Relevant excerpt shown below. This uses RandNorm (also in the linked webpage) which is a pair of numbers from a unit normal distribution, and in MATLAB you should be able to use randn(2,1)
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Function RandSkew(fAlpha As Single, _
Optional fLocation As Single = 0, _
Optional fScale As Single = 1, _
Optional bVolatile As Boolean = False) As Single
' shg 2008-0919
' http://azzalini.stat.unipd.it/SN/faq.html
' Returns a random variable with skewed distribution
' fAlpha = skew
' fLocation = location
' fScale > 0 = scale
Dim sigma As Single
Dim afRN() As Single
Dim u0 As Single
Dim v As Single
Dim u1 As Single
If bVolatile Then Application.Volatile
Randomize (Timer)
sigma = fAlpha / Sqr(1 + fAlpha ^ 2)
afRN = RandNorm()
u0 = afRN(1)
v = afRN(2)
u1 = sigma * u0 + Sqr(1 - sigma ^ 2) * v
RandSkew = IIf(u0 >= 0, u1, -u1) * fScale + fLocation
End Function
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