Re: Re: work only with Performance->Speed

*To*: mathgroup at smc.vnet.net*Subject*: [mg102841] Re: [mg102838] Re: work only with Performance->Speed*From*: DrMajorBob <btreat1 at austin.rr.com>*Date*: Sun, 30 Aug 2009 06:05:29 -0400 (EDT)*References*: <200908291030.GAA00283@smc.vnet.net>*Reply-to*: drmajorbob at yahoo.com

Interesting... but Mathematica often successfully plots functions which, at one point or many, is undefined... simply leaving them out. Bobby On Sat, 29 Aug 2009 05:30:45 -0500, Bill Rowe <readnews at sbcglobal.net> wrote: > On 8/27/09 at 6:32 AM, btreat1 at austin.rr.com (DrMajorBob) wrote: > >> You have an extra comma (syntax error!), but this fails, too: > >> ContourPlot3D[ >> zz (-1 + 1/(xx^2 + yy^2 + zz^2)^(3/2)), {xx, -2, 2}, {yy, -2, 2}, >> {zz, -4, 4}, BoundaryStyle -> Red, RegionFunction -> Function[{x, y, >> z}, x^2 + y^2 + z^2 >= 1], PerformanceGoal -> "Quality"] >> >> "Speed" works, but "Quality" does not. It looks like a bug to me. > > I am not so sure this is a bug. The expression becomes 0+0/0 for > xx=yy=zz=0. When "Speed" is chosen, I assume the algorithm > samples the expression at far fewer points and likely misses the > singularity. Conversely, when "Quality" is chosen the > singularity isn't missed. I would guess the issue is due to the > presence of this singularity. > > -- DrMajorBob at yahoo.com

**References**:**Re: work only with Performance->Speed***From:*Bill Rowe <readnews@sbcglobal.net>