<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">All,<div><br></div><div>I can't see why the code below is producing this error:</div><div><br></div><div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Monaco" size="2" style="font: 10.0px Monaco">! Missing number, treated as zero.</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Monaco" size="2" style="font: 10.0px Monaco"><to be read again> </font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Monaco" size="2" style="font: 10.0px Monaco"> !</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Monaco" size="2" style="font: 10.0px Monaco">l.15 <span class="Apple-tab-span" style="white-space:pre"> </span>\psxTick[linecolor=red](1.5){x_0}</font></div><p style="margin: 0.0px 0.0px 0.0px 0.0px; min-height: 14.0px"><font face="Monaco" size="2" style="font: 10.0px Monaco"> </font><br class="khtml-block-placeholder"></p><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Monaco" size="2" style="font: 10.0px Monaco">? </font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font class="Apple-style-span" face="Monaco" size="2"><span class="Apple-style-span" style="font-size: 10px;"><br></span></font></div></div><div><div>\documentclass[12pt]{article}</div><div><br></div><div>\usepackage{pst-pdf}</div><div>\usepackage{pst-bar}</div><div>\usepackage{pstricks-add}</div><div>\usepackage{pst-plot}</div><div>\usepackage{pst-tree}</div><div><br></div><div>\begin{document}</div><div><br></div><div>\begin{center}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\psset{unit=0.125in}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\begin{pspicture}(-8,-2)(8,0.5)</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\psaxes[arrowscale=1.5,arrows=<->,yAxis=false,labels=none](0,0)(-8,0)(8,0)</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\psxTick[linecolor=red](1.5){x_0}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\uput[270](0,0){$0$}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\uput[270](7,0){$7$}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\psdots*[linecolor=red,dotsize=3pt 3](#sa,0)(#sb,0)(#sc,0)(#sd,0)</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\end{pspicture}</div><div>\end{center}</div><div><br></div><div>\end{document}</div></div></body></html>