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<font face="Myriad Pro">Dear David,<br>
<br>
thanks for your explanations:<br>
<br>
Here an approach with psplot -- however only working for positive
slopes \geq 1. I am not clever enough to put in some if/else commands.<br>
<br>
slope > 1 _CHECKED_, <br>
0< slope <1 {X-RANGE -5 ... 5}<br>
and for negative <br>
slope < -1 <br>
-1 < slope < 0 {X-RANGE -5 ... 5}<br>
<br>
Maybe there is someone cleverer out there to refine this approach:<br>
<br>
\documentclass{article}<br>
\usepackage{pstricks,pstricks-add}<br>
\begin{document}<br>
\pagestyle{empty}<br>
\newcommand{\DaveArnold}[4]{%<br>
\psset{unit=0.5}<br>
\begin{pspicture}(-6,-6)(6,6)<br>
\psgrid[gridcolor=lightgray,gridlabels=0pt,subgriddiv=1](0,0)(-5,-5)(5,5)<br>
\psaxes[labels=none,ticks=none]{->}(0,0)(-5.5,-5.5)(5.5,5.5)<br>
\Cnode[radius=0.1cm,fillstyle=solid,fillcolor=blue,linecolor=blue](#1,#2){A}<br>
\Cnode[radius=0.1cm,fillstyle=solid,fillcolor=blue,linecolor=blue](#3,#4){B}<br>
\psclip{\psframe[linestyle=none](-5,-5)(5,5)}<br>
%\ncline[nodesep=10cm,linecolor=blue]{<->}{A}{B}<br>
\psplot[arrows=<->,linecolor=blue]{5 neg #2 sub #3 #1 sub #4 #2
sub div mul #1 add}{5 #2 sub #3 #1 sub #4 #2 sub div mul #1 add}{#4 #2
sub #3 #1 sub div x #1 sub mul #2 add}<br>
\endpsclip<br>
\uput[0](5.5,0){$x$}<br>
\uput[90](0,5.5){$y$}<br>
\end{pspicture}<br>
\resetOptions<br>
}<br>
<br>
\DaveArnold{-4}{-2}{-3}{4}<br>
%First Argument x-Koordinate Point A<br>
%Second Argument y-Koordinate Point A<br>
%Third Argument x-Koordinate Point B<br>
%Fourth Argument y-Koordinate Point B<br>
<br>
\DaveArnold{-1}{-2}{3}{3} \DaveArnold{-4}{-4}{1}{2}<br>
<br>
\DaveArnold{0}{0}{2}{1} \DaveArnold{-4}{4}{1}{2}<br>
\end{document} <br>
<br>
<br>
Regards,<br>
<br>
Juergen<br>
</font><br>
David Arnold wrote:
<blockquote
cite="mid:41E09418-A2C0-4522-B8E9-A41AA98F466C@suddenlink.net"
type="cite">Jurgen et al,
<div><br>
</div>
<div>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.</div>
<div><br>
</div>
<div>When I teach, I tell the students that the arrow has the same
meaning as the ellipses at the end of this sequence:</div>
<div><br>
</div>
<div>1, 3, 5, 7, ...</div>
<div><br>
</div>
<div>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.</div>
<div><br>
</div>
<div>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).</div>
<div><br>
</div>
<div>For example, see the discussion on Domain and Range in the
Intermediate Algebra Text we wrote for our students:</div>
<div><br>
</div>
<div><a moz-do-not-send="true"
href="http://msenux.redwoods.edu/IntAlgText/chapter2/section3.pdf">http://msenux.redwoods.edu/IntAlgText/chapter2/section3.pdf</a></div>
<div><br>
</div>
<div>D.</div>
<div><br>
</div>
<div><br>
<div>
<div>On Dec 29, 2008, at 12:17 PM, Juergen Gilg wrote:</div>
<br class="Apple-interchange-newline">
<blockquote type="cite"> <font face="Myriad Pro">Dear Arnold,<br>
<br>
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??? <br>
Inmidst of the circlepoint = not visible, due to the radius of the
circle...<br>
<br>
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?<br>
<br>
I always imagine when having an arrowhead, that there is a DIRECTION...
Just to widen my horizon of didactics.<br>
<br>
Regard,<br>
<br>
Juergen<br>
<br>
</font><br>
David Arnold wrote:
<blockquote
cite="mid:1420E242-210E-446A-9D44-1739B44DAADE@suddenlink.net"
type="cite">Jurgen,
<div><br>
</div>
<div>Good ideas here. I would not thought of this solution.</div>
<div><br>
</div>
<div>One point: At my end, the lines don't have arrows at each
end. They're line segments.</div>
<div><br>
</div>
<div>Is there a fix for this?</div>
<div><br>
</div>
<div>D.</div>
<div><br>
</div>
<br>
<hr size="4" width="90%"><br>
<div><br>
<div>
<div>On Dec 29, 2008, at 11:55 AM, Juergen Gilg wrote:</div>
<br class="Apple-interchange-newline">
<blockquote type="cite"> Dear David,<br>
<br>
couldn't solve the problem with 2 arrowhead at the end of the lines
drawn, however the rest should work fine.<br>
<blockquote
cite="mid:75312BDB-3C9E-4889-BB03-F935A656FE73@suddenlink.net"
type="cite">
<pre wrap="">Looking for ideas.
</pre>
</blockquote>
<pre class="moz-signature" cols="65"><font color="#003300">\documentclass{article}
\usepackage{pstricks,pstricks-add}
\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)
\Cnode[radius=0.1cm,fillstyle=solid,fillcolor=blue,linecolor=blue](#1,#2){A}
\Cnode[radius=0.1cm,fillstyle=solid,fillcolor=blue,linecolor=blue](#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} </font>
</pre>
<br>
Regards,<br>
<br>
Juergen<br>
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</blockquote>
</div>
<br>
</div>
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</blockquote>
<br>
<pre class="moz-signature" cols="65">--
Jürgen Gilg
Austr. 59
70376 Stuttgart
-------------------------------------
Tel 0711.59 27 88
e-Mail <a moz-do-not-send="true" class="moz-txt-link-abbreviated"
href="mailto:gilg@acrotex.net">gilg@acrotex.net</a>
Websites <a moz-do-not-send="true" class="moz-txt-link-abbreviated"
href="http://www.acrotex.net">www.acrotex.net</a>
<a moz-do-not-send="true" class="moz-txt-link-abbreviated"
href="http://www.brueckenkurs-physik.de">www.brueckenkurs-physik.de</a>
<a moz-do-not-send="true" class="moz-txt-link-abbreviated"
href="http://www.gilligan-online.de">www.gilligan-online.de</a>
</pre>
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</blockquote>
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</div>
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</pre>
</blockquote>
<br>
<pre class="moz-signature" cols="65">--
Jürgen Gilg
Austr. 59
70376 Stuttgart
-------------------------------------
Tel 0711.59 27 88
e-Mail <a class="moz-txt-link-abbreviated" href="mailto:gilg@acrotex.net">gilg@acrotex.net</a>
Websites <a class="moz-txt-link-abbreviated" href="http://www.acrotex.net">www.acrotex.net</a>
<a class="moz-txt-link-abbreviated" href="http://www.brueckenkurs-physik.de">www.brueckenkurs-physik.de</a>
<a class="moz-txt-link-abbreviated" href="http://www.gilligan-online.de">www.gilligan-online.de</a>
</pre>
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