<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: times new roman,new york,times,serif; font-size: 12pt; color: #000000'>The question is: how do you want to represent complex numbers in your 3D plot? <br>plot3d function only represent the real part...<br><br>Serge Steer<br><br><hr id="zwchr"><blockquote style="border-left:2px solid #1010FF;margin-left:5px;padding-left:5px;color:#000;font-weight:normal;font-style:normal;text-decoration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;"><b>De: </b>"Ubirajara Marques da Cruz" <biracruz@cemig.com.br><br><b>À: </b>users@lists.scilab.org<br><b>Envoyé: </b>Vendredi 7 Juin 2013 22:46:37<br><b>Objet: </b>[Scilab-users] Problems with plot 3d. Function fplot3d<br><br>
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<p class="MsoNormal">To user support,</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Recently I was studing a function that i wanted to plot it. This function is a 3d equation that I wrote above:</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";mso-fareast-language:PT-BR"><img id="_x0000_i1025" src="cid:image004.png@01CE63A6.F58C59E0" height="21" width="144"></span></p>
<p class="MsoNormal">I try to use fplot3d to plot following interval x=0:0.01:1 and y=0:0.01:3.
</p>
<p class="MsoNormal">When I analise the results this function has positive and negative numbers to plot but when i plot it it only show positive numbers.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">I look for the answers about square root of negative numbers and i found help tips that show into this case the answer is a complex number. Then I see that matrix z is a vector that has real numbers and complex numbers(they are mixed)
and fplot3d shows a result very diferente of I was expecting.</p>
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<p class="MsoNormal">If point is a real number fplot3d plot right surface and if the point is a complex number it shows a wrong surface. What must i do to solve this problem?</p>
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<p class="MsoNormal">Follow, I send code that I´ve been use into scilab 4.1.2 (scipad)</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">x=0:0.01:1 ;y=0:0.01:3</p>
<p class="MsoNormal">deff(‘z=f(x,y)’,’z=( (1-exp(-5*x))-y)^(1/3)’)</p>
<p class="MsoNormal">clf()</p>
<p class="MsoNormal">fplot3d(x,y,f,alpha=60,theta=60)</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><img id="Imagem_x0020_3" src="cid:image007.jpg@01CE63A6.F58C59E0" height="529" width="423"></p>
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<p class="MsoNormal">Down part of this graphic is mirrored to up side and values are wrong. The right result that i was expecting is the surface to be drawnt to negative side.</p>
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<p class="MsoNormal">Thank you for yours helps.</p>
<p class="MsoNormal"> </p>
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