# [pstricks] Automate a line drawing routine

Mon Dec 29 21:27:49 CET 2008

Jurgen et al,

I would not pick points P and Q that lie on the boundary. So I would
want the arrows at the end of the lines where the lines exit on a
boundary of the grid.

When I teach, I tell the students that the arrow has the same meaning
as the ellipses at the end of this sequence:

1, 3, 5, 7, ...

They mean "etcetera." The arrow at the end of the line means much the
same thing. Enough of the pattern has been established so that you
can intuit the rest of the behavior of the function. For example, it
moves up and to the right indefinitely.

This type of instruction comes in handy when discussing the domain
and range of functions from a graphical viewpoint with the students.
We do a number of examples where we have segments, rays, and lines,
and they have different effects on the domain (or range).

For example, see the discussion on Domain and Range in the
Intermediate Algebra Text we wrote for our students:

http://msenux.redwoods.edu/IntAlgText/chapter2/section3.pdf

D.

On Dec 29, 2008, at 12:17 PM, Juergen Gilg wrote:

> Dear Arnold,
>
> where should appear the arrowheads, if the line ends in: (-5,-5),
> (-5,5), (5,-5), (-5,5)  in the 4 CORNERS of your grid???
> Inmidst of the circlepoint = not visible, due to the radius of the
> circle...
>
> Just a general question: Why do you like to have arrowheads in a
> functionplot? Any didactial aspects? I am definitely not used to
> that. To show that the line does not end at that point?
>
> I always imagine when having an arrowhead, that there is a
> DIRECTION... Just to widen my horizon of didactics.
>
> Regard,
>
> Juergen
>
>
> David Arnold wrote:
>>
>> Jurgen,
>>
>> Good ideas here. I would not thought of this solution.
>>
>> One point: At my end, the lines don't have arrows at each end.
>> They're line segments.
>>
>> Is there a fix for this?
>>
>> D.
>>
>>
>>
>>
>> On Dec 29, 2008, at 11:55 AM, Juergen Gilg wrote:
>>
>>> Dear David,
>>>
>>> couldn't solve the problem with 2 arrowhead at the end of the
>>> lines drawn, however the rest should work fine.
>>>> Looking for ideas.
>>>>
>>> \documentclass{article}
>>> \begin{document}
>>> \pagestyle{empty}
>>>
>>> \newcommand{\DaveArnold}[4]{%
>>> \psset{unit=0.5}
>>> \begin{pspicture}(-6,-6)(6,6)
>>> \psgrid[gridcolor=lightgray,gridlabels=0pt,subgriddiv=1](0,0)
>>> (-5,-5)(5,5)
>>> \psaxes[labels=none,ticks=none]{->}(0,0)(-5.5,-5.5)(5.5,5.5)
>>> (#1,#2){A}
>>> (#3,#4){B}
>>> \psclip{\psframe[linestyle=none](-5,-5)(5,5)}
>>> \ncline[nodesep=10cm,linecolor=blue]{<->}{A}{B}
>>> \endpsclip
>>> \uput[0](5.5,0){$x$}
>>> \uput[90](0,5.5){$y$}
>>> \end{pspicture}
>>> \resetOptions
>>> }
>>>
>>> \DaveArnold{1}{2}{-3}{5}
>>> %First Argument     x-Koordinate Point A
>>> %Second Argument    y-Koordinate Point A
>>> %Third Argument     x-Koordinate Point B
>>> %Fourth Argument    y-Koordinate Point B
>>>
>>> \DaveArnold{-1}{-2}{3}{3}
>>>
>>> \DaveArnold{-5}{-5}{1}{2}
>>>
>>> %NO PROBLEM to so produce vertical and horizontal lines as well.
>>> \end{document}
>>>
>>>
>>> Regards,
>>>
>>> Juergen
>>> _______________________________________________
>>> PSTricks mailing list
>>> PSTricks at tug.org
>>> http://tug.org/mailman/listinfo/pstricks
>>
>> _______________________________________________
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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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