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I want to make a filled Ellipsoid, but it seems Filling options doesn't work in Graphics options. I have a matrix

matrix1={{1,4},{6,8}}

thus I plot en ellipse from his Eigenvalues and Eigenvectors

valmat = Eigenvalues@matrix1;
vecmat = Eigenvectors@matrix1;
pair = {0.5, 0.5}
ellips1 = 
Ellipsoid[pair, {Abs[valmat[[1]]], Abs[valmat[[2]]]}, {vecmat[[1]], vecmat[[2]]}];
plot1 = Graphics[{Red, ellips1}, GridLines -> Automatic, 
GridLinesStyle -> Directive[Gray, Dotted]];
partot1 = 
Show[plot1, Frame -> True, 
FrameLabel -> {Style["x", 18], Style["y", 18]}, AspectRatio -> 1, 
FrameTicks -> {Automatic, Automatic, None, None}, 
LabelStyle -> Directive[13], ImageSize -> 500]

enter image description here

The question is how to filled this ellipse with an specific color??..and also (if it's possible) the transparency on that. Thanks

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  • $\begingroup$ What's Ellipsoid, what pacage is required? $\endgroup$ – Kuba♦ Sep 20 '13 at 13:38
  • $\begingroup$ @Kuba Needs["MultivariateStatistics`"] $\endgroup$ – ybeltukov Sep 20 '13 at 13:38
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    $\begingroup$ Perhaps use Disk? $\endgroup$ – bobthechemist Sep 20 '13 at 13:39
  • $\begingroup$ Use a disk, scale the axis and rotate. $\endgroup$ – rm -rf♦ Sep 20 '13 at 13:40
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    $\begingroup$ Also, ellipsoid is a graphics, so you need to use faceform/edgeform. See this answer where I use an ellipsoid. $\endgroup$ – rm -rf♦ Sep 20 '13 at 13:42
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If there is nothing else:

partot1 /. Line -> Polygon

enter image description here

partot1 /. Line[x_] -> {Green, EdgeForm@Thick, FaceForm[Opacity@.5], Polygon[x]}

enter image description here

Fortunatelly Elipsoid is not ReadProtected so you can use ?? to se the UpValues related to it. (I suggest to Ctrl+F and replace/delete all contexts: MultivariateStatistics`Private so the code will be transparent)

Really quick and not elegant fix for 2d case:

style[opts__, x_Ellipsoid] := Graphics[x] /. Line[y_] :> {opts, Polygon[y]} // First

ellips1 = Ellipsoid[{0.5`, 0.5`}, {10., 1.52}, {{0.4, 1.}, {-1.58, 1.}}];

Graphics[{
          style[Red, ellips1],
          Rotate[style[Green, EdgeForm@Thick, Opacity@.5, ellips1]
                 , Pi/2]
         }, Frame -> True ]

You can use ?? like I said before to create more general solution, unfortunatelly I'm run out of time now :/. Good luck.

enter image description here

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  • $\begingroup$ @AlejandroGuarnizo I'm glad you like it. It is good habit to hold on with an accept a little bit. It can discourage otheres. Here for example might be some easy fix I don't know because I'm not familiar with this package :) $\endgroup$ – Kuba♦ Sep 20 '13 at 14:00
  • $\begingroup$ Thanks @Kuba for your answer, it works. But now I have other one. What if instead one ellipse, I have two. It seems there is no way to show somehow one behind the other? $\endgroup$ – Alejandro Guarnizo Sep 20 '13 at 14:06
  • $\begingroup$ @AlejandroGuarnizo The overlap problem is much harder and has been discussed a number of time in this site. A quick search shows this mathematica.stackexchange.com/questions/28997/…. Id suggest if you cant find a satisfactory existing answer you should post that as a new question. $\endgroup$ – george2079 Sep 20 '13 at 14:27
  • $\begingroup$ another link: mathematica.stackexchange.com/questions/11146/… $\endgroup$ – george2079 Sep 20 '13 at 14:32
  • $\begingroup$ @AlejandroGuarnizo Take a look at my edit, does it work for you? $\endgroup$ – Kuba♦ Sep 20 '13 at 19:33

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