Let me advertize that sage-flatsurf (https://github.com/flatsurf/sage-flatsurf) has an implementation of the hyperbolic plane with exact coordinates
The following code ``` from flatsurf import HyperbolicPlane H = HyperbolicPlane(AA) z0 = H.point(2*AA(2).sqrt()/3 - 1, 4/6, model='half_plane') z1 = H.point(-1, 0, model='half_plane') print(z0) g = H.geodesic(z0, z1) print(g.start()) print(g.end()) ``` gives the correct ``` -0.05719095841793663? + 0.6666666666666667?*I 0.4142135623730951? -1 ``` Best Vincent On Tue, 13 Aug 2024 at 17:50, dmo...@deductivepress.ca <dmor...@deductivepress.ca> wrote: > > This was previously reported as issue #32362 on github, so any further > discussion should take place there. The solution suggested there is to have > sagemath calculate endpoints in the Poincare disk model, instead of in the > upper half plane model. > > On Sunday, August 11, 2024 at 7:45:18 AM UTC-4 Hakan Granath wrote: >> >> Hi, >> >> There is a bug in hyperbolic_polygon which happens quite rarely, but for >> example >> >> l = [-1, 1, -0.0571909584179366 + 0.666666666666667*I] >> hyperbolic_polygon(l, model='PD') >> >> results in an incorrectly drawn hyperbolic triangle. It seems to be a subtle >> numerical issue; if the last element of l is replaced with >> -0.0571909584179366 + 0.667*I everything looks fine. >> >> Digging a bit further, there seems to be an underlying issue here: >> >> PD = HyperbolicPlane().PD() >> z0 = CC(-0.0571909584179366 + 0.666666666666667*I) >> z1 = CC(-1) >> PD.get_geodesic(z0, z1).ideal_endpoints() >> >> yields the erroneous result >> >> [Boundary point in PD -9.52420782539595e-17 + 1.00000000000000*I, >> Boundary point in PD -0.800000000000000 + 0.600000000000000*I] >> >> (the second endpoint should be -1). Because of this I am suspicious of lines >> 1267 - 1269 in src/sage/geometry/hyperbolic_space/hyperbolic_geodesic.py. >> There we have the code >> >> # We could also have a vertical line with two interior points >> if x1 == x2: >> return [M.get_point(x1), M.get_point(infinity)] >> >> Maybe the if statement should instead be something like >> >> if abs(x1 - x2) < EPSILON: >> >> Best regards, >> >> Håkan Granath >> > -- > You received this message because you are subscribed to the Google Groups > "sage-devel" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sage-devel+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sage-devel/baff7122-26e0-40a1-8bbf-0f2fc36e88d2n%40googlegroups.com. -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-devel/CAGEwAAn%2BzU_XE2H%3DgDX0Vvvarfh-UoSGwU0YX5eDrm2rEFtqWw%40mail.gmail.com.
