[pstricks] computed coordinates

[Juergen Gilg]

Dear Zbiginiew,

please try that -- this works fine for me:

\multido{\rx=-1.5+0.12}{26}{%
\multido{\ry=0+0.06}{26}{%
\pstThreeDLine[arrows=->]%
(\rx,\ry,0)%
(\rx\space ,\ry\space, \rx\space 2 exp \ry\space 2 exp add)
}
}

Regards,

Juergen

Zbigniew Nitecki wrote:
> I want to use multido to draw arrows from the xy-plane to the graph of 
> z=x^2 +y^2 for a collection
> of points in the rectangle [-1.5,1.5]\times[0,1.5].  The following code
> *********************************************************************************
> \multido{\rx=-1.5+0.12}{26}{%
> \multido{\ry=0+0.06}{26}{%
> \pstThreeDLine[arrows=->]%
> (\rx,\ry,0)%
> (!\rx\space \ry\space \rx\space 2 exp \ry\space 2 exp add)
> }
> }
> *************************************************************************************
> produces no errors, but also produces no arrows.  If I try to define a 
> function
> **************************************************************************************
> \newcommand{\hit}[2]{! #1\space 2 exp #2\space 2 exp add}
> ****************************************************************************************
> and replace the last set of coordinates with
> *****************************************************
> (\rx, \ry, \hit{\rx}{\ry})
> *******************************************************
> I get the error message
> ********************************************************
> Runaway definition?
> ->/ArrowA { moveto } def /ArrowB { BeginArrow 1.  1.  scale  false 0.\ETC.
> ! TeX capacity exceeded, sorry [main memory size=1500000].
> \pst at code ...sub x2 x1 sub Atan def ArrowA x1 Alph
>                                                   a cos arrowlength 
> mul add ...
> l.52 }
> ********************************************************
> (This I almost understand:  I am trying to use a latex command to 
> define a postscript function---so how do I do that?)
> So just to test things I tried
> *******************************
> \multido{\rx=-1.5+0.12}{26}{%
> \multido{\ry=0+0.06}{26}{%
> \pstThreeDLine[arrows=->]%
> (\rx,\ry,0)%
> % (!\rx\space \ry\space \rx\space 2 exp \ry\space 2 exp add)
> % (\rx, \ry, \hit{\rx}{\ry})
> (\rx,\ry,1)
> }
> }
> ******************************************
> and got no error, but still no arrows.  Now I am really confused. 
>  What have I screwed up now?
>
> My real question, though, is:
> Is there a way to use mutlido with commands like \pstThreeDLine in 
> which certain coordinates depend in a non-trivial way on the multido 
> parameter?
>
>
> Zbigniew Nitecki
>
> Department of Mathematics
>
> Tufts University
>
> Medford, MA 02155
>
>
> telephones:
>
> Office    (617)627-3843
>
> Dept.    (617)627-3234
>
> Dept. fax    (617)627-3966
>
> http://www.tufts.edu/~znitecki/ <http://www.tufts.edu/%7Eznitecki/>
>
> ------------------------------------------------------------------------
>
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>   

-- 
 Jürgen Gilg
 Austr. 59
 70376 Stuttgart
-------------------------------------
 Tel       0711.59 27 88
 e-Mail    gilg at acrotex.net
 Websites  www.acrotex.net
           www.brueckenkurs-physik.de
           www.gilligan-online.de

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