Re: Re: Re: Re: Locator question
- To: mathgroup at smc.vnet.net
- Subject: [mg79548] Re: [mg79526] Re: [mg79452] Re: [mg79433] Re: Locator question
- From: Murray Eisenberg <murray at math.umass.edu>
- Date: Sun, 29 Jul 2007 00:07:21 -0400 (EDT)
- Organization: Mathematics & Statistics, Univ. of Mass./Amherst
- References: <f86r55$pc7$1@smc.vnet.net> <200707250930.FAA26363@smc.vnet.net> <f89pve$5jn$1@smc.vnet.net> <200707261030.GAA09683@smc.vnet.net> <12053562.1185538119591.JavaMail.root@m35> <op.tv4rezijqu6oor@monster.gateway.2wire.net> <8266975.1185567612261.JavaMail.root@m35> <200707280940.FAA00083@smc.vnet.net>
- Reply-to: murray at math.umass.edu
An "obvious" (?) typo: I meant 6.0.1, of course.
DrMajorBob wrote:
> I didn't know Locators existed at ALL, before version 6.
>
> Yet this code works in v 5.0.1 and NOT in v 6???
>
> (I have continually updated WinXP and Mathematica 6.0.1.)
>
> Bobby
>
> On Fri, 27 Jul 2007 15:15:41 -0500, Murray Eisenberg
> <murray at math.umass.edu> wrote:
>
>> Under Windows XP with Mathematica 5.0.1, and with the version of
>> trackPointOnPlot nearest the top of my posting, I see only one locator!
>>
>> DrMajorBob wrote:
>>> That code gives me two locators, neither of them on the curve. One
>>> can't be "grabbed", but it moves when I move the other one. If I move
>>> the second locator to the curve, the other also moves to the curve, at
>>> another point (but sometimes beyond the left limit of the plot).
>>> Bizarro!
>>> Am I the only one seeing this?
>>> Bobby
>>> On Fri, 27 Jul 2007 04:48:07 -0500, Murray Eisenberg
>>> <murray at math.umass.edu> wrote:
>>>
>>>> Very nice! An observation and a question:
>>>>
>>>> 1. Probably it would be more reasonable that the third, optional,
>>>> argument be not an {x,y} point, but instead the x-coordinate of that
>>>> point, since the point is supposed to be on the graph anyway. The
>>>> modification for that is trivial:
>>>>
>>>> trackPointOnPlot[f_, {a_, b_}, strt_: Automatic] :=
>>>> Module[{start = strt /. Automatic -> a},
>>>> DynamicModule[{p = {start, f[start]}},
>>>> Column[{LocatorPane[Dynamic[p, (p = {First@#, f[First@#]})
>>>> &],
>>>> Plot[f[x], {x, a, b}]], Dynamic[p]}]]]
>>>>
>>>> 2. Where/how did you discover the "trick" of using Automatic as a
>>>> default value for an argument? I don't recall seeing that before.
>>>>
>>>> Albert wrote:
>>>>> ...The following is my attempt to solve your issue, it only uses one
>>>>> definition, but introduces some extra code...
>>>>>
>>>>> trackPointOnPlot[f_, {a_, b_}, strt_: Automatic] :=
>>>>> Module[{start = strt /. Automatic -> {a, f[a]}},
>>>>> DynamicModule[{p = start},
>>>>> Column[{LocatorPane[Dynamic[p, (p = {First@#, f[First@#]}) &],
>>>>> Plot[f[x], {x, a, b}]], Dynamic[p]}]]
>>>>> ]
>>>> Of course, per your suggestion, a simpler way but now using only the
>>>> x-coordinate as third, optional, argument is:
>>>>
>>>> trackPointOnPlot[f_, {a_, b_}, start_] :=
>>>> DynamicModule[{p = {start, f[start]}},
>>>> Column[{LocatorPane[Dynamic[p, (p = {First@#, f[First@#]})
>>>> &],
>>>> Plot[f[x], {x, a, b}]], Dynamic[p]}]]
>>>>
>>>> trackPointOnPlot[f_, {a_, b_}] := trackPointOnPlot[f, {a, b}, a]
>>>>
>
>
>
--
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: Albert <awnl@arcor.net>
- Re: Locator question
- From: Albert <awnl@arcor.net>
- Re: Re: Re: Locator question
- From: DrMajorBob <drmajorbob@bigfoot.com>
- Re: Locator question