RegionPlot appears to have regressed in version 10.4

In 10.3.1

RegionPlot[ImplicitRegion[x^2 + y^2 == 1, {x, y}]]


enter image description here

But in 10.4 both

RegionPlot[ImplicitRegion[x^2 + y^2 == 1, {x, y}]]


RegionPlot[x^2 + y^2 == 1, {x, -1, 1}, {y, -1, 1}]


enter image description here

However, 10.4 knows that this is a valid region.

DiscretizeRegion@ImplicitRegion[x^2 + y^2 == 1, {x, y}]

enter image description here

Can anyone else confirm this?

Win 7 Pro 64 bit.

  • 1
    $\begingroup$ Same on linux, however RegionPlot[0.99 <= x^2 + y^2 <= 1.01, {x, -1, 1}, {y, -1, 1}, PlotPoints -> 200] this works. $\endgroup$ Mar 6 '16 at 10:59
  • $\begingroup$ I sent product feedback to Wolfram Tech Support on this issue. $\endgroup$
    – Bob Hanlon
    Mar 6 '16 at 14:39
  • $\begingroup$ This could just be a case of the function catching up with the documentation, as the help page for RegionPlot in both versions states "RegionPlot can in general only find regions of positive measure; it cannot find regions that are just lines or points" $\endgroup$
    – Jason B.
    Apr 8 '16 at 9:46

This is not an answer but rather an extended comment demonstrating another aspect of the problem.


(*  "10.4.0 for Mac OS X x86 (64-bit) (February 26, 2016)"  *)

If the region is given some thickness it is displayed:

  ImplicitRegion[1 - 10^(-n) <= x^2 + y^2 <= 1 + 10^(-n), {x, y}]], {{n, 7}, 
  Range[10], ControlType -> SetterBar}]

enter image description here

However, when the thickness is made too small, another problem arises: the region displays as if it were a disk.

enter image description here


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