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Bug fixed in 10.1.0

R = RegionUnion[Disk[{0, 0}, 1, {0, Pi}], Disk[{1/2, 0}, 1/2]] // 
  RegionDifference[#, RegionUnion[Disk[{1/2, 0}, 1/6], Disk[{-1/2, 0}, 1/2]]] &
(dr = DiscretizeRegion[R]) // Timing

If you run this codes in many times, you will find that it will give a result in 1 second with 50% probability,while it will not give a result in 100s with 50% probability.

win7 v10.0.2

Perhaps it is related to the performance of computer. The better the computer performance,the greater probability it gives a result in 1 second. If we run this codes in Wolfram Programming Cloud, it always give a result in 1 second.

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  • 2
    $\begingroup$ Please do not use the bugs tag until the issue has been confirmed as a bug by WRI or the Mathematica.SE community. $\endgroup$
    – m_goldberg
    Commented Feb 7, 2015 at 14:39
  • $\begingroup$ What do you mean by "Sometimes"? Why do you think it should always finish the computation in less than 100 seconds? $\endgroup$
    – m_goldberg
    Commented Feb 7, 2015 at 14:42
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    $\begingroup$ I can reproduce the problem, also on Windows 7 V10.0.2. Seems like a bug, but I'll let others decide on that. $\endgroup$
    – DumpsterDoofus
    Commented Feb 7, 2015 at 16:07
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    $\begingroup$ I can reproduce it in V10.0.2, Mac OSX 10.10.2. Not surprisingly it also happens with Needs["NDSolveFEM"]; ToElementMesh[R]. It does not happen with the option Method -> "RegionPlot", but the cusp is truncated. $\endgroup$
    – Michael E2
    Commented Feb 8, 2015 at 13:37
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    $\begingroup$ Seems fixed in current development code. $\endgroup$
    – user21
    Commented Feb 9, 2015 at 11:23

1 Answer 1

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As mentioned by user21 in the comments, this bug has been fixed as of version 10.1.0.

Table[(RegionUnion[Disk[{0, 0}, 1, {0, Pi}], Disk[{1/2, 0}, 1/2]] // 
         RegionDifference[#,RegionUnion[Disk[{1/2, 0}, 1/6], Disk[{-1/2, 0}, 1/2]]] &) //  
           DiscretizeRegion // AbsoluteTiming // First, {100}] // Mean       

(* 0.142127 *)
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