[pstricks] Re : Re : Re : Elektrostatic Field
Herbert Voss
Herbert.Voss at FU-Berlin.DE
Mon Jan 18 14:52:29 CET 2010
Am 18.01.2010 10:49, schrieb mluque5130 at aol.com:
>
> It would be interesting to generalize to any number of electrical charges. Here's an example with four charges. It's beautiful!
very nice
the same, a bit shorter. Can be modified to use n charges ...
\documentclass{article}
\usepackage{pstricks-add}
\SpecialCoor
\def\FieldLinesFourElectricCharges{
1 1 4 { /i ED xP i getX sub yP i getY sub Pyth } for
4 array astore /Radius ED
0 0
1 1 4 { /i ED
i getQ xP i getX sub mul i getR 3 exp Div add exch
i getQ yP i getY sub mul i getR 3 exp Div add exch
} for
/Ex ED
/Ey ED
/NormeE Ex Ey Pyth def
/dX Ex NormeE div pasX mul def
/dY Ey NormeE div pasX mul def
}
\begin{document}
\begin{center}
\begin{pspicture*}(-5,-5)(5,5)
% les limites
\multido{\iB=1+1}{4}{%
\multido{\iA=0+15}{24}{% 24 lignes de champ
\psparametricplot[plotpoints=2000]{xmin}{xmax}[{
/xmin -5 def /xmax 5 def /ymin -5 def /ymax 5 def
/pasX xmax xmin sub 200 div def % 0.05
/Qcharge [1 1 1 1] def
/Xcoor [ -2.5 2.5 2.5 -2.5 ] def
/Ycoor [ -2.5 -2.5 2.5 2.5 ] def
/getX { 1 sub Xcoor exch get } def
/getY { 1 sub Ycoor exch get } def
/getQ { 1 sub Qcharge exch get } def
/getR { 1 sub Radius exch get } def
/xStart \iB\space getX def
/yStart \iB\space getY def
/pasX \iB\space getQ dup abs Div 0.05 mul def
/xP xStart pasX \iA\space cos mul add def
/yP yStart pasX \iA\space sin mul add def
}]{\FieldLinesFourElectricCharges
/xP xP dX add def /yP yP dY add def xP yP } %
}
}
\end{pspicture*}
\end{center}
\end{document}
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