Yes, 1/v[1] is an AlgebraicNumber. I think this is a conversion failure in the ImplicitSurface class, for which I will file a ticket. For the moment your workaround seems like the best option.
-Marshall Hampton On Jan 11, 3:47 pm, BFJ <[email protected]> wrote: > I'm not sure why nothing appears and no warning or error is raised. It > may have to do with the type of v[1]. Try this: > > {{{ > M = matrix(3,[1,-1,-1,-1,3,1,-1,1,3]); v=M.eigenvalues(); > x,y,z = var('x,y,z') > Q=implicit_plot3d(x^2+y^2+z^2==RDF(1/v[1]), [x,-3,3], [y,-3,3], > [z,-3,3], opacity=0.5); Q > > }}} > > I see a sphere. Changing 1/v[1] to RDF(1/v[1]) coerces 1/v[1] into the > field of real numbers RDF. > > On Jan 6, 11:56 am, pong <[email protected]> wrote: > > > Here are the code: > > > M = matrix(3,[1,-1,-1,-1,3,1,-1,1,3]); v=M.eigenvalues(); v > > > [2, 0.4384471871911698?, 4.561552812808830?] > > > Q=implicit_plot3d(x^2+y^2+z^2==1/v[1], [x,-3,3], [y,-3,3],[z,-3,3], > > opacity=0.5); Q > > > Jmol shows nothing. However, if I change 1/v[1] to 2.28 (~1/v[1]) then > > it shows the sphere. > > > Any idea why? -- To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
