Bug introduced In 10.1 or earlier and fixed 11.1
Consider the following ParametricRegion
from an answer to this question:
region = ParametricRegion[{{(1 + r - 12 r^2 + 4 r^3)/(2 r - 2),
z Sqrt[(4 r^2)/(r - 1)^2 (r - r^2 (r - 3)^2)]},
2 < r < 4 && -1 < z < 1}, {r, z}];
Now let's discretize this region using various versions of Mathematica starting from 10.1:
DiscretizeRegion[region]
Something is seriously wrong here, seems like a progression from 10.1 to 10.2, then a serious (let's call it a bug) regression from 10.2 to 10.3. 10.4 just gets the region wrong. The problem seems to be with ParametricRegion
and how Mathematica handles them because I get similar wrong results with RegionPlot
too. Can anyone confirm these?