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Re: How show Locator point and its image under a function?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg79894] Re: [mg79866] How show Locator point and its image under a function?
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Wed, 8 Aug 2007 04:50:33 -0400 (EDT)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <200708070532.BAA12064@smc.vnet.net>
  • Reply-to: murray at math.umass.edu

I oversimplified my requirements...

Actually, I want to do more: I want to include a LocatorAutoCreate->All 
option for the left-hand graphics portion so that as each point there is 
clicked it remains there and its image in the right-hand graphics is 
automatically shown an remains showing even as I click new points on the 
left.

Murray Eisenberg wrote:
> The following code displays a fixed point and its image under a 
> specified function f:
> 
>    f[{x_,y_}]:={2x+1,y+2}
>    Module[{pt = {-1, 0.5}},
>       Row[{
>         Framed@Graphics[Point[pt], PlotRange -> 5],
>         Framed@Graphics[Point[f[pt]], PlotRange -> 5]
>       }]
>     ]
> 
> Now I want to have the point in the left-hand graphic to be dynamic, 
> controlled by a Locator, and to have its changed image under the 
> function to be shown in the right-hand graphic.
> 
> The idea is something like the following (WRONG!) code:
> 
>    DynamicModule[{pts={{0,0}}},
>      Row[{
>        LocatorPane[Dynamic[pts],Graphics[{},PlotRange->5]],
>        Graphics[Dynamic[f/@pts],PlotRange->5]
>      }]
>    ]
> 
> That code produces error messages, "1 is not a Graphics primitive or 
> directive", "2 is not a Graphics primitive or directive".
> 
> How can it actually be done?
> 

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305


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