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

• To: mathgroup at smc.vnet.net
• Subject: [mg79963] Re: How show Locator point and its image under a function?
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Thu, 9 Aug 2007 05:32:33 -0400 (EDT)
• Organization: Uni Leipzig
• References: <200708070532.BAA12064@smc.vnet.net> <f9c0jv$5st$1@smc.vnet.net>
• Reply-to: kuska at informatik.uni-leipzig.de

Hi,

f[{x_, y_}] := {(2 x + 1), y + 2}

DynamicModule[{lst = {{-1, 1/2}}},

  Row[{LocatorPane[Dynamic[lst],
       Framed@ Graphics[{}, PlotRange -> 10, ImageSize -> 300],
     LocatorAutoCreate -> True],
      Framed@
     Graphics[{RGBColor[1, 0, 0], Dynamic[Point[f[#]] & /@ lst]},
      PlotRange -> 10, ImageSize -> 300]}
   ]
  ]


should work.

Regards
   Jens

Murray Eisenberg wrote:
> 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?
>>
> 

• References:
  • How show Locator point and its image under a function?
    • From: Murray Eisenberg <murray@math.umass.edu>