3D plot of an ellipsoid

Hi, I have to plot the following function on a 3d graph, it should be an ellipsoid. theta_ is a 1x3 vector and COV a 3x3 matrix

RC=@(x,y,z) (theta_-[x y z])*inv(COV)*(theta_-[x y z])'-5;

Answer 1

[John D'Errico]

theta_ = [1 2 3];
COV = cov(rand(10,3)); % picking some arbitrary values for theta_ and COV...
RC=@(x,y,z) (theta_-[x y z])*inv(COV)*(theta_-[x y z])'-5;

fimplicit3(RC)

Warning: Function behaves unexpectedly on array inputs. To improve performance, properly vectorize your function to return an output with the same size and shape as the input arguments.

axis equal
box on
xlabel x
ylabel y
zlabel z

[Simone Fiumi]

Thank you!