Bug in Manipulate with Trigger control?

*To*: mathgroup at smc.vnet.net*Subject*: [mg92750] Bug in Manipulate with Trigger control?*From*: "michael.p.croucher at googlemail.com" <michael.p.croucher at googlemail.com>*Date*: Sun, 12 Oct 2008 04:32:43 -0400 (EDT)

Hi all I have been playing around with Manipulate a bit and am wondering about the behavior of the code below Manipulate[ theta = pointnum*2 Pi/128.; x = r Cos[theta]; y = r Sin[theta]; Pointlist[[pointnum]] = Point[{x, y}]; Graphics[{PointSize[Large], Point[{x, y}], {PointSize[Small], Pointlist}}, PlotRange -> {{-5, 5}, {-5, 5}}] , {r, 2, 4} , {pointnum, 1, 129, 1, ControlType -> Trigger, DisplayAllSteps -> True, AnimationRepetitions -> 10} , TrackedSymbols -> {pointnum, r}, Initialization :> {Pointlist = Table[{}, {129}]} ] When the pointnum trigger is pressed a big point traces a circle and leaves a trail of smaller points behind it. In my current setup (6.0.0 on windows) the trail is sometimes incomplete despite the fact that I have asked for DisplayAllSteps->True The code above always seems to misses the 78th point on my machine. Does anyone know what is going on? Finally, AnimationRate doesn't work as expected. Putting AnimationRate->64 should take 2 seconds for a complete circle but it takes longer. It's 2am so maybe I am just being dense and everything is behaving as it should be...another pair of eyes would be greatly appreciated. Cheers, Mike