<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:14pt"><div>Hi folks,</div><div><br></div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;">According to Christoph Bersch in his answer (http://tex.stackexchange.com/a/167578/19356)</div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;">AlgParser wrongly parses, for example, N-A.x or A.x when we are working in infix form (aka algebraic).</div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent;
font-style: normal;"><br></div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;">A solution by buffering the values as follows,</div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;">\makeatletter\pst@Verb{/Ax N-A.x def}\makeatother<br></div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;">seems to be complicated.</div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style:
normal;"><br></div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;">In my humble opinion, why don't we deprecate the format N-<nodename>.x (as well as N-<nodename>.y, <nodename>.x and <nodename>.y) and replace them with safe ones such as</div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><nodename>x (as well as <nodename>y)?</div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><br></div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue',
Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><br></div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><br></div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;">\documentclass[pstricks,border=12pt]{standalone}</div><div>\usepackage{pst-eucl,pstricks-add}</div><div><br></div><div>\def\f(#1){((#1)*(#1-5)*(#1-6)/4+1.5*(#1)-5)}</div><div>\def\m(#1,#2){(\f(#2)-\f(#1))/(#2-#1)}</div><div>\def\fp(#1){Derive(1,\f(#1))}%
f'(x) </div><div><br></div><div>\def\L#1{\uput[-90](#1|0,0){$#1\mathstrut$}\uput[180](0,0|#1){$f(#1)$}\psCoordinates[linestyle=dashed,linecolor=gray](#1)}</div><div><br></div><div>\begin{document}</div><div><br></div><div>\begin{pspicture}[algebraic,saveNodeCoors,PointSymbol=none,PointName=none](-1,-1)(8,8)</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\psaxes[labels=none,ticks=none]{->}(0,0)(-.5,-.5)(7.5,7.5)[$x$,0][$y$,90]</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\pstGeonode(*1 {\f(x)}){a}(*6.5 {\f(x)}){b}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\makeatletter\pst@Verb{/ax N-a.x def /bx N-b.x def}\makeatother</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\psplot[linecolor=blue]{ax}{bx}{\f(x)}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\pstInterFF{\m(ax,bx)}{\fp(x)}{4}{temp}</div><div><span
class="Apple-tab-span" style="white-space:pre"> </span>\pstGeonode(*N-temp.x {\f(x)}){c}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\pcline[nodesep=-1,linecolor=green](a)(b)</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\psxline[linecolor=red](c){.1(a)-.1(b)}{.1(b)-.1(a)}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\psset{linecolor=gray,linestyle=dashed}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\foreach \i in {a,b,c}{\L{\i}}</div><div>\end{pspicture}</div><div><br></div><div>\end{document}</div><div><br></div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;">Thank you in advance.</div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial,
'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><br></div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;">best regards,</div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><br></div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;">Weirdstress Function</div><div style="color: rgb(0, 0, 0); font-size: 19px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style:
normal;">(http://tex.stackexchange.com/users/19356)</div></div></body></html>