# How to plot 3d implicit surface

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## How to plot 3d implicit surface

 Hello, I would like to plot a 3d implicit surface defines with an equation like f(x, y, z)=0. There's no parametric transformation and is not possible to express for example z=g(x, y). Does anyone have an idea ? Thank a lot.
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## Re: How to plot 3d implicit surface

 Le 23/11/12 09:14, Orbeman a écrit : > Hello, > > I would like to plot a 3d implicit surface defines with an equation like > f(x, y, z)=0. There's no parametric transformation and is not possible to > express for example z=g(x, y). > > Does anyone have an idea ? > > Thank a lot. > > > > -- > View this message in context: http://mailinglists.scilab.org/How-to-plot-3d-implicit-surface-tp4025307.html> Sent from the Scilab users - Mailing Lists Archives mailing list archive at Nabble.com. > _______________________________________________ > users mailing list > [hidden email] > http://lists.scilab.org/mailman/listinfo/usersWhat is your equation ? S. _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users
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## Re: How to plot 3d implicit surface

 In fact, I have several equations like this : x^2+y^2+x+y+x*y+z^2-1=0 I can express z=sqrt(1-...) but in a general case...
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## Re: How to plot 3d implicit surface

 Orbeman wrote In fact, I have several equations like this : x^2+y^2+x+y+x*y+z^2-1=0 I can express z=sqrt(1-...) but in a general case... In the general case I usually use isosurfaces to plot implicit functions. Since I am completely new to scilab I do not know if it is just a lack of my ability to find a corresponding method in scilab of if there is none to plot isosurfaces. If there is none and there is interest in having one I could adapt the Octave function I wrote a few years ago and which is since then part of their software to work in scilab and also the implicit function for plotting the zero level surfaces of 3d functions.
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## Re: How to plot 3d implicit surface

 Am 25.11.2012 00:40, schrieb Martin Helm: > Orbeman wrote >> In fact, I have several equations like this : >> >> x^2+y^2+x+y+x*y+z^2-1=0 >> >> I can express z=sqrt(1-...) but in a general case... I found this one http://www.scilab.org/contrib/index_contrib.php?page=displayContribution&fileID=1236have not tested it yet but looks promising. _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users
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## Re: How to plot 3d implicit surface

 Am 25.11.2012 01:32, schrieb Martin Helm: > I found this one > http://www.scilab.org/contrib/index_contrib.php?page=displayContribution&fileID=1236> have not tested it yet but looks promising. I tested it now: Take the function contour3d.sci from the link above. It seems to be an old function which uses a few deprecated function calls. You need to change line 36 and replace xbas() with gcf() in addition you need to replace in line 82 sort with gsort. Now you can run the following simple test function val = isotest(x, y,z)     val = x.^2+y.^2+x+y+x.*y+z.^2-1; endfunction clf(); x = linspace(-2, 2, 31); y = x; z = x; [X Y Z] = meshgrid(x,y,z); val = isotest(X, Y, Z); contour3d(X, Y, Z, val, 0) f = gcf(); f.color_map = [1 0 0]; // make the black surface red which will draw your implicit function in red. This will work for all kind of implicit functions as long as your discretisation is fine enough. Hope that helps. _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users
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## Re: How to plot 3d implicit surface

 In reply to this post by Martin Helm Le 25/11/2012 01:32, Martin Helm a écrit : > Am 25.11.2012 00:40, schrieb Martin Helm: >> Orbeman wrote >>> In fact, I have several equations like this : >>> >>> x^2+y^2+x+y+x*y+z^2-1=0 >>> >>> I can express z=sqrt(1-...) but in a general case... > I found this one > http://www.scilab.org/contrib/index_contrib.php?page=displayContribution&fileID=1236> have not tested it yet but looks promising. Yes, a more recent version has been released on fileexchange instead of the old contributions repository: http://fileexchange.scilab.org/toolboxes/contour3d_______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users