Re: newbie: can't Manipulate ListPlot of recurrence
- To: mathgroup at smc.vnet.net
- Subject: [mg96818] Re: newbie: can't Manipulate ListPlot of recurrence
- From: Albert Retey <awnl at gmx-topmail.de>
- Date: Wed, 25 Feb 2009 04:07:14 -0500 (EST)
- References: <go0j40$n0f$1@smc.vnet.net>
Tom Roche wrote: > summary: I'm trying to Manipulate the logistic map. I can ListPlot it, > but when I try to Manipulate, the UI behaves weirdly. > > details: > > As advertised by the Subject:, I'm new to Mathematica (specifically > 7.0.0 for Students for 32-bit Windows on XP Pro) so please excuse any > lapses in terminology. I'd also appreciate pointers to specific docs > rather than just an RTFM. > > I'm trying to model the logistic map y=a y (1-y): > > http://en.wikipedia.org/wiki/Logistic_map > http://mathworld.wolfram.com/LogisticMap.html > http://www.phy.duke.edu/~palmer/notebooks/LogisticMap.nb > > To start with I just tried to plot it, which works: > > Clear[a, y]; > a=3.5; > y=0.4; > ListPlot[Table[y=a y (1-y),{50}],Joined->True] > > I'd like to Manipulate a and y, but when I try to > > Clear[a, y]; > Manipulate[ > ListPlot[Table[y=a y (1-y),{50}],Joined->True], {{a, 3.5}, 0, 4}, > {{y, 0.4}, 0, 1}] > > I get weird behavior: > > 1 initially the y slider oscillates > > 2 initially the plot displays but flashes (apparently between two > phases) until I click one of the sliders > > 3 the y slider will not move > > 4 the a slider can be dragged, but to no effect (i.e. the plot does > not change) all these come from the fact that you are asigning to y which is one of the variables that you want to manipulate, which is almost never a good idea... > 5 there are no error messages > What am I doing wrong? and how can I Manipulate this map? I think this does what you want: Clear[a, y]; Manipulate[ ListPlot[ Block[{x = y}, Table[x = a x (1 - x), {50}] ], Joined -> True, PlotRange -> {0, 1} ], {{a, 3.5}, 0, 4}, {{y, 0.4}, 0, 1} ] hth, albert