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Re: plotting a normal distribution curve

by Till Tantau-3 :: Rate this Message:

Am 04.07.2006 um 20:21 schrieb Shanks N:

> Hello,
>
> I'm trying to make a picture similar to
>
> http://en.wikipedia.org/wiki/Image:Standard_deviation_diagram.png
>
> using tikz.
>
> A search on google revealed y= (1/A)*EXP( (-x**2)/B ) sort of
> approximates the normal curve. I plugged this into an awk script and
> generated the data from x= -4 to +4.
>
> Now, How do I plot this using Latex/Tikz to get something similar
> to the
> picture?
>
> regards,
> shanks
>
>
> Using Tomcat but need to do more? Need to support web services,
> security?
> Get stuff done quickly with pre-integrated technology to make your
> job easier
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> Geronimo
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Hi!

try this (with gnuplot installed and working):

\begin{tikzpicture}[scale=1.25]
\colorlet{col1}{blue!70}
\colorlet{col2}{blue!60}
\colorlet{col3}{blue!50}
\colorlet{col4}{blue!40}

\draw [help lines] (-4.25,-1.25) grid (4.25,1.5);
\draw [help lines,step=0.25cm] (-2.99,0) grid (2.99,0.99);

\draw[->] (0,-1.25) -- (0,1.5) node [above]
{$\displaystyle\frac{1}{\sigma\sqrt{2\pi}}\exp\biggl(\frac{-x^2}
{2\sigma^2}\biggr)$};

\begin{scope}[smooth,draw=gray!20,y=0.3989422804cm]
\filldraw [fill=col3] plot[id=f1,domain=-3:-2] function {exp(-
x*x/2)} -- (-2,0) -- (-3,0) -- cycle;
\filldraw [fill=col2] plot[id=f2,domain=-2:-1] function {exp(-
x*x/2)} -- (-1,0) -- (-2,0) -- cycle;
\filldraw [fill=col1] plot[id=f3,domain=-1:0] function {exp(-
x*x/2)} -- (0,0) -- (-1,0) -- cycle;
\filldraw [fill=col1] plot[id=f4,domain=0:1] function {exp(-
x*x/2)} -- (1,0) -- (0,0) -- cycle;
\filldraw [fill=col2] plot[id=f5,domain=1:2] function {exp(-
x*x/2)} -- (2,0) -- (1,0) -- cycle;
\filldraw [fill=col3] plot[id=f6,domain=2:3] function {exp(-
x*x/2)} -- (3,0) -- (2,0) -- cycle;

\draw[black] plot[id=f7,domain=-4.25:4.25,samples=100] function
{exp(-x*x/2)};
\end{scope}

\draw[->] (-4.25,0) -- (4.25,0) node [right] {$x$};

\foreach \pos/\label in {-3/$-3\sigma$,-2/$-2\sigma$,-1/$-\sigma$,
1/$\sigma$,2/$2\sigma$,3/$3\sigma$}
\draw (\pos,0) -- (\pos,-0.1) (\pos cm,-3ex) node
[anchor=base,fill=white,inner sep=1pt] {\label};

\draw (-0.1,1) -- (.1,1) node [right,fill=white,inner sep=1pt] {$
\sigma$};

\foreach \pos/\percent/\height in
{1/34/0.5,2/14/0.25,3/2/0.125,4/0.1/0.1}
{
\node[text=col
\pos,anchor=base,yshift=2pt,xshift=-0.625cm,fill=white,inner sep=1pt]
at (\pos,\height) {$\percent\%$};
\node[text=col\pos,anchor=base,yshift=2pt,xshift=.
625cm,fill=white,inner sep=1pt] at (-\pos,\height) {$\percent\%$};
}
\end{tikzpicture}

Best regards,
Till

--
Prof. Dr. Till Tantau <tantau@...>
http://www.tcs.uni-luebeck.de

Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
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