Fixed Typo in Code---> Re: updating a simulation within Manipulate.

*To*: mathgroup at smc.vnet.net*Subject*: [mg130063] Fixed Typo in Code---> Re: updating a simulation within Manipulate.*From*: W Craig Carter <ccarter at MIT.EDU>*Date*: Thu, 7 Mar 2013 22:47:41 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <9C229A0A-D12F-4D3E-9B5F-7FA8B918CFE6@mit.edu>

On previous message, there is a typo in the example code, please use this instead: randomStep[bias_, stepList_] := Module[{angle = RandomVariate[NormalDistribution[bias, 1]]}, Join[stepList, {Last[stepList] + {Cos[angle], Sin[angle]}}]] walkerGraphic[stepList_, range_] := Graphics[GraphicsComplex[stepList, Disk /@ Range[Length[stepList]]], PlotRange -> range {{-1, 1}, {-1, 1}}] DynamicModule[{walkerPath = {{0, 0}}}, Manipulate[ If[keepWalking,(*kludge warning---testing for If[ True...] seems inefficient*) walkerPath = randomStep[bias, walkerPath]]; If[reset, reset = False; keepWalking = False; walkerPath = {{0, 0}}]; walkerGraphic[walkerPath, range], {{keepWalking, False}, {True, False}}, {{reset, False}, {True, False}}, Delimiter, {{range, 20}, 0, 100}, {{bias, 0}, -Pi, Pi, AngularGauge[##, ImageSize -> 160, ScaleOrigin -> {{-4 Pi, 4 Pi}, 1}] &}]] W Craig Carter Professor of Materials Science, MIT On Mar 7, 13, at 17:16 PM, W Craig Carter wrote: > I *think* I've asked this question before, but I can't find it on mathgroup. In any case, I don't know the answer now. > > Here is a simple example of a Manipulate that updates a graphic as long as a boolean is true. This method seems like a kludge to me---is it? If so, what would be a better way to do this. > > This is a constructed example, the real case I am looking at is much more involved; but kudos to anyone who can make a reasonable facsimile of their signature by adjusting the random walker's bias.... > > randomStep[bias_, stepList_] := > Module[{angle = RandomVariate[NormalDistribution[bias, 1]]}, > Join[stepList, {Last[stepList] + {Cos[angle], Sin[angle]}}]] > > walkerGraphic[stepList_, range_] := > Graphics[GraphicsComplex[stepList, Disk /@ Range[Length[stepList]]], > PlotRange -> range {{-1, 1}, {-1, 1}}] > > DynamicModule[ > {walkerPath = {{0, 0}}}, > Manipulate[ > If[keepWalking, (* kludge warning---testing for If[True...] seems inefficient *) > walkerPath = randomStep[bias, walkerPath] > ]; > If[reset, > reset = False; keepWalking = False; > walkerPath = {{0, 0}} > ]; > walkerGraphic[walkerPath, range], > {{keepWalking, False}, {True, False}}, > {{reset, False}, {True, False}}, > Delimiter, > {{range, 20}, 0, 100}, > {{a, 0}, -Pi, Pi, > AngularGauge[##, ImageSize -> 160 , > ScaleOrigin -> {{-4 Pi, 4 Pi}, 1}] &} > ] > ] > > > > W Craig Carter > Professor of Materials Science, MIT > >