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Re: Manipulate

  • To: mathgroup at smc.vnet.net
  • Subject: [mg86294] Re: Manipulate
  • From: m.r at inbox.ru
  • Date: Fri, 7 Mar 2008 02:33:33 -0500 (EST)
  • References: <fqlmn4$jcj$1@smc.vnet.net>

On Mar 5, 2:47am, N K <nk200... at yahoo.com> wrote:
> Hi,
> I just have started using Mathematica and was working on the Manipulate function. I have the following piece of code:
>
> Manipulate[
> Print[value],
> {value, 1, 10, 1, ControlType -> Animator}
> ]
> which seems to work just fine. However, if I add the following line to it, it does not quite work.
>
> lst = {};
> Manipulate[
> lst = Append[lst, value];
> Print[value],
>  {value, 1, 10, 1, ControlType -> Animator}
> ]
>
> The values that are being printed for "value" are really weird and incorrect.
> Any suggestions on what I have done wrong?
>
> Thanks very much,

The problem here is that a dynamic update is triggered every time lst
is modified and you need to monitor only the changes of Manipulate
variables. In 6.0.2 you can use

lst = {};
Manipulate[AppendTo[lst, value],
 {value, 1, 10, 1, Animator},
 TrackedSymbols :> {value}]

or, equivalently, TrackedSymbols -> Manipulate.

Maxim Rytin
m.r at inbox.ru


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