[pstricks] pst-funct: strange psGaussI behavior

[Herbert Voss]

Am 04.05.2012 20:53, schrieb Andrzej Pacut:
> There is a strange behavior of \psGaussI function (part of pst-func
> package). I understood this function was the integral of Gaussian
> density. Running a simple test below I began to doubt:
>
> \psset{xunit=2,yunit=20mm}

\psset{xunit=2,yunit=20mm,Simpson=10}

works for me.

Herbert

>
> \begin{pspicture}(-2,-.5)(2,2)
> \psaxes[Dy=0.25]{->}(0,0)(-2,0)(2,1.25)
> \uput[-90](6,0){x} \uput[0](0,1){y}
> \psGaussI[mue=-1.5,sigma=0.2]{-1.7}{1.7}
> \psGaussI[mue=-1.0,sigma=0.2]{-1.7}{1.7}
> \psGaussI[mue=-0.5,sigma=0.2]{-1.7}{1.7}
> \psGaussI[mue=-0.0,sigma=0.2]{-1.7}{1.7}
> \psGaussI[mue= 0.5,sigma=0.2]{-1.7}{1.7}
> \psGaussI[mue= 1.0,sigma=0.2]{-1.7}{1.7}
> \psGaussI[mue= 1.5,sigma=0.2]{-1.7}{1.7}
> \end{pspicture}
>
> Only the plots for mue=-1 and mue=-0.5 look according to my expectation
> (which might be erroneous). Now,
>
> 1)For mue =-1.5, the plot has a horizontal asymptote at about 0.8. This
> may show that psGaussI is not the Gaussian distribution function, but
> rather a running integral of Gausian density, with the left integral
> bound=-1.7 in my example. Am I right? If so, is it a way to plot a real
> Gaussian distribution?
>
> 2)All plots for mue greater than -0.5 fluctuate, showing a behavior far
> from the one I would expect from a distribution function, or even from
> the integral of a density function. Changing Simpson parameter does not
> change the story.
>
> I will be grateful for any help
>
> Andrzej Pacut
>
> Faculty of Electronics and Information Technology
>
> Warsaw University of Technology
>
> Warsaw, Poland
>
>
>
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