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

*To*: mathgroup at smc.vnet.net*Subject*: [mg79931] Re: [mg79905] Re: How show Locator point and its image under a function?*From*: Murray Eisenberg <murray at math.umass.edu>*Date*: Thu, 9 Aug 2007 05:15:49 -0400 (EDT)*Organization*: Mathematics & Statistics, Univ. of Mass./Amherst*References*: <f990t4$c2d$1@smc.vnet.net> <200708080856.EAA05959@smc.vnet.net>*Reply-to*: murray at math.umass.edu

Oops, I missed the Point wrapper for the image points. Thanks. And now LocatorAutoCreate -> All in the LocatorPane also satisfies the additional requirement I stated in a follow-up to my original post: allow multiple locator points to be created on the fly and their images automatically to be shown. f[{x_, y_}] := {2 x + 1, y + 2} DynamicModule[{pts = {{0, 0}}}, Row[{ LocatorPane[Dynamic[pts], Graphics[{}, PlotRange -> 5], LocatorAutoCreate -> All], Graphics[Dynamic[Point /@ f /@ pts], PlotRange -> 5] }] ] David Bailey wrote: > 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, > > You forgot to make Point objects in your Graphics! > > DynamicModule[{pts = {{0, 0}}}, > Row[{LocatorPane[Dynamic[pts], Graphics[{}, PlotRange -> 5]], > Graphics[Dynamic[Point /@ f /@ pts], PlotRange -> 5]}]] > > David Bailey > http://www.dbaileyconsultancy.co.uk > -- 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

**References**:**Re: How show Locator point and its image under a function?***From:*David Bailey <dave@Remove_Thisdbailey.co.uk>