Re: Re: Locator question
- To: mathgroup at smc.vnet.net
- Subject: [mg79327] Re: [mg79292] Re: [mg79272] Locator question
- From: Murray Eisenberg <murray at math.umass.edu>
- Date: Wed, 25 Jul 2007 01:57:59 -0400 (EDT)
- Organization: Mathematics & Statistics, Univ. of Mass./Amherst
- References: <2851721.1185180232088.JavaMail.root@m35> <200707240956.FAA25082@smc.vnet.net>
- Reply-to: murray at math.umass.edu
The Locator is NOT tracking along the curve. That is, it is not
constrained to be on the curve. The locator can be at any ({x,y} in the
figure, although the point of tangency is, of course, constrained to lie
on the curve plotted.
DrMajorBob wrote:
> How's this?
>
> Manipulate[
> Show[
> Plot[g[x], {x, 0, 2 \[Pi]}],
> p[[2]] = g@p[[1]]; slope = D[g[x], x] /. x -> p[[1]];
> Plot[p[[2]] + slope (x - p[[1]]), {x, 0, 2 \[Pi]}],
> PlotLabel ->
> Style["slope of f(x)= " <>
> ToString[NumberForm[slope, {6, 4}]]]], {{g, Sin,
> "function"}, {Sin -> TraditionalForm[Sin[x]],
> Cos -> TraditionalForm[Cos[x]], #^2 & -> TraditionalForm[x^2]},
> ControlType -> PopupMenu}, {{p, {0, 0}}, Locator}]
>
> Bobby
>
> On Mon, 23 Jul 2007 02:40:52 -0500, Mike <mjp.1 at comcast.net> wrote:
>
>> All,
>>
>> I'm trying to get the locator to track a point along a given curve:
>>
>>
>> bothfandtan[g_, p_] :=
>> Module[{f = g,
>> eqline = (D[g, x] /. x -> p[[1]]) (x - p[[1]]) + p[[2]]},
>> Show[{Plot[f, {x, 0, 2 \[Pi]}], Plot[eqline, {x, 0, 2 \[Pi]}]}]]
>>
>> Manipulate[
>> Show[bothfandtan[g, p],
>> PlotLabel ->
>> Style["slope of f(x)= " <>
>> ToString[NumberForm[D[g, x] /. x -> p[[1]], {6, 4}]]]],
>> {{g, Sin[x], "function"},
>> {Sin[x] -> TraditionalForm[Sin[x]],
>> Cos[x] -> TraditionalForm[Cos[x]],
>> x^2 -> TraditionalForm[x^2]}}, {{p, {0, 0}}, Locator},
>> SaveDefinitions -> True]
>>
>>
>> I've tried a number of possibilities, but I can't seem to get this to
>> work. Mathematica's help section on this isn't very helpful.
>>
>> Thanks for the help...
>>
>> Mike
>>
>>
>
>
>
--
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: Locator question
- From: DrMajorBob <drmajorbob@bigfoot.com>
- Re: Locator question