Re: Can a Locator be Made to Track a Curve?
- To: mathgroup at smc.vnet.net
- Subject: [mg120792] Re: Can a Locator be Made to Track a Curve?
- From: DrMajorBob <btreat1 at austin.rr.com>
- Date: Wed, 10 Aug 2011 06:46:59 -0400 (EDT)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <201108060612.CAA13010@smc.vnet.net>
- Reply-to: drmajorbob at yahoo.com
I don't see anything unexpected, using the code below.
The function derivative is high (relative to the scale of the plot) in
that region, so {x, f@x} is sensitive to the value of x, and hence, it's
difficult to place the cursor precisely where you want it. I never saw it
get "stuck".
Bobby
On Tue, 09 Aug 2011 06:19:45 -0500, E. Martin-Serrano
<eMartinSerrano at telefonica.net> wrote:
> Try this slightly modified version and see what happens for 0<x< 1
>
> locator = Graphics[{Red, Disk[{0, 0}, Offset[3]], Black, Circle[{0,
> 0},
> Offset[3]], Circle[{0, 0}, Offset[6]] }, ImageSize -> 30];
>
> f[x_] := Sin[x] E^-x;
> g[{x_, _}] := {x, f@x}
> pt = {0, 0};
> LocatorPane[Dynamic[pt, (pt = g@#) &], Plot[f[x], {x, 0, 2 Pi}],
> Appearance
> -> locator]
>
> The locator tends to go out of control for 0<x< 1. I observed this,
> say,
> abnormal behavior for all versions posted; after changing f[x_] :=
> Sin[x]
> to f[x_] := Sin[x] E^-x. It seems the problem is not related to the
> inclusion of the tailored locator (works the same for the built in one).
> Sometimes the locator tends to jump or get stuck within 0<x< 1 range.
>
>
> -----Mensaje original-----
> De: DrMajorBob [mailto:btreat1 at austin.rr.com]
> Enviado el: lunes, 08 de agosto de 2011 10:21
> Para: mathgroup at smc.vnet.net
> Asunto: Re: Can a Locator be Made to Track a Curve?
>
> A bit simpler, I think, is:
>
> f[x_] := Sin[x];
> g[{x_, _}] := {x, f@x}
> pt = {0, 0};
> LocatorPane[Dynamic[pt, (pt = g@#) &], Plot[Sin[x], {x, 0, 2 Pi}]]
>
> Bobby
>
> On Sun, 07 Aug 2011 05:14:52 -0500, Heike Gramberg
> <heike.gramberg at gmail.com> wrote:
>
>> You could do something like
>>
>> f[x_] := Sin[x];
>> pt = {0, 0};
>> LocatorPane[Dynamic[pt, (pt[[1]] = #[[1]]; pt[[2]] = f[#[[1]]]) &],
>> Plot[Sin[x], {x, 0, 2 Pi}]]
>>
>> Heike
>>
>> On 6 Aug 2011, at 08:12, Gregory Lypny wrote:
>>
>>> Hello everyone,
>>>
>>> Can a locator be constrained so that it tracks a curve?
>>>
>>> Regards,
>>>
>>> Gregory
>>>
>>
>>
>
>
> --
> DrMajorBob at yahoo.com
>
>
--
DrMajorBob at yahoo.com
- References:
- Can a Locator be Made to Track a Curve?
- From: Gregory Lypny <gregory.lypny@videotron.ca>
- Can a Locator be Made to Track a Curve?