# How to fill an area interval under a gaussian

I want to know if it's possible to fill an area interval (i.e from -0.2 to 0.2) under a gaussian curve, more exactly just an interval under this curve, using PSTricks.

I'm using pst-func, pst-plot, pst-math, pstricks-add packages also. Based on pst-func package

\psset{yunit=4cm,xunit=3}
\begin{pspicture}(-2,-0.2)(2,1.4)
\psgrid[griddots=10,gridlabels=0pt, subgriddiv=0]
\psaxes[Dy=0.25]{->}(0,0)(-2,0)(2,1.25)
\uput[-90](6,0){x}\uput[0](0,1){y}
\rput[lb](1,0.75){\textcolor{red}{$\sigma =0.5$}}
\rput[lb](1,0.5){\textcolor{blue}{$\sigma =1$}}
\rput[lb](-2,0.5){$f(x)=\dfrac{1}{\sigma\sqrt{2\pi}}\,e^{-\dfrac{(x-\mu)^2}{2\sigma{}^2}}$}
\psGauss[linecolor=red, linewidth=2pt, fillcolor=red!40,fillstyle=solid,opacity=0.5]{-2.95}{2.95}%
\psGaussI[linewidth=1pt]{-2}{2}%
%  \psGauss[linecolor=cyan, mue=0.5, linewidth=2pt]{-1.75}{1.75}%
%  \psGauss[sigma=1, linecolor=blue, linewidth=2pt]{-1.75}{1.75}
\end{pspicture}


Edited:

I tryed this code:

\psset{yunit=4cm,xunit=3}
\begin{pspicture}(-2,-0.2)(2,1.4)
\psgrid[griddots=10,gridlabels=0pt, subgriddiv=0]
\psaxes[Dy=0.25]{->}(0,0)(-2,0)(2,1.25)
\uput[-90](6,0){x}\uput[0](0,1){y}
\rput[lb](1,0.75){\textcolor{red}{$\sigma =0.5$}}
\rput[lb](1,0.5){\textcolor{blue}{$\sigma =1$}}
\rput[lb](-2,0.5){$f(x)=\dfrac{1}{\sigma\sqrt{2\pi}}\,e^{-\dfrac{(x-\mu)^2}{2\sigma{}^2}}$}
\psGauss[linecolor=red, linewidth=2pt]{-2.95}{2.95}%
\psGaussI[linewidth=1pt]{-2}{2}%
\pscustom[fillstyle=solid,fillcolor=red!30]{%
\psGauss[linewidth=1pt,nue=5]{0.5}{1}%
\psline(1,0)(0.5,0)}
\end{pspicture}


And I would like to know if it's possible to close the loop line (psline), that start over the curve and lay down on axis "x". From 0.5 to 1 over the curve, then 1 to (1,0) and to (0.5,0). Seem's that is missing a part from (0.5,0) to (0.5,curve). There is a way to fill this line ?

Thanks again!!

• is there any problem to read the documentation: "14.1 Filling an area under a distribution curve" – user2478 Feb 20 '13 at 20:26
• wow, didn't see it. thank you very much – André Feb 20 '13 at 20:32