<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">I am trying to plot the surface z=4x^2 +y^2 but only for values z<=1; I am trying to do this by<div>plotting a "vertical slice" at y=\ry via a multido. What's wrong with this code?</div><div><br></div><div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\begin{pspicture}(-5,-5)(5,2)</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\multido{\ry=-0.1+0.1}{19}{</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\parametricplotThreeD(!%</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>0.5 1 \ry\space dup mul sub 0.5 exp mul neg,</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>0.5 1 \ry\space dup mul sub 0.5 exp mul){%</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>t %</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\ry %</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>t dup mul 4 mul \ry\space dup mul add%</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\end{pspicture}</div><div><br></div><div>I get the error message </div><div apple-content-edited="true"><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><br></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Error: /undefined in !0.5</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Operand stack:</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> tMin</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Execution stack:</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> %interp_exit .runexec2 --nostringval-- --nostringval-- --nostringval-- 2 %stopped_push --nostringval-- --nostringval-- --nostringval-- false 1 %stopped_push 1905 1 3 %oparray_pop 1904 1 3 %oparray_pop 1888 1 3 %oparray_pop 1771 1 3 %oparray_pop --nostringval-- %errorexec_pop .runexec2 --nostringval-- --nostringval-- --nostringval-- 2 %stopped_push --nostringval--</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Dictionary stack:</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> --<a href="dict:1148/1684(ro)(G)--">dict:1148/1684(ro)(G)--</a> --<a href="dict:0/20(G)--">dict:0/20(G)--</a> --<a href="dict:119/200(L)--">dict:119/200(L)--</a> --<a href="dict:177/300(L)--">dict:177/300(L)--</a> --<a href="dict:38/200(L)--">dict:38/200(L)--</a> --<a href="dict:122/200(L)--">dict:122/200(L)--</a></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Current allocation mode is local</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Last OS error: 2</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Current file position is 138589</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">GPL Ghostscript 8.62: Unrecoverable error, exit code 1</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">### FAILED to generate /tmp/altpdflatex.22827-1234884508/picturetest1.pdf ()</div><div><br></div><div><br></div><div>Or is there a way to do this via clipping? (ie, \psplotThreeD(-1,1)(-1,1){x dup mul 4 mul y dup mul add} followed by a clipping command that only allows z<=1)</div></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><br></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Zbigniew Nitecki</font></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Department of Mathematics</font></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Tufts University</font></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Medford, MA 02155</font></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; "><br></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">telephones:</font></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Office<span class="Apple-converted-space"><span class="Apple-converted-tab"> <span class="Apple-converted-space"> </span></span></span>(617)627-3843</font></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Dept.<span class="Apple-converted-space"><span class="Apple-converted-tab"> <span class="Apple-converted-space"> </span></span></span>(617)627-3234</font></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Dept. fax<span class="Apple-converted-space"><span class="Apple-converted-tab"> <span class="Apple-converted-space"> </span></span></span>(617)627-3966</font></p><a href="http://www.tufts.edu/~znitecki/">http://www.tufts.edu/~znitecki/</a></span> </div><br></div></body></html>