Constrain locator
- To: mathgroup at smc.vnet.net
- Subject: [mg121706] Constrain locator
- From: Tom De Vries <tidetabletom at gmail.com>
- Date: Mon, 26 Sep 2011 20:05:30 -0400 (EDT)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
Hello everyone,
I'm looking for a simple way to constrain a locator to a particular function.
I've seen a few methods given by posters to this group and others.
In programs like Sketchpad and Geogebra you can add a point to a
function and immediately constrain the point to that function.
You can then "trace" the point, displaying coordinates, etc.
I'm trying to work within Mathematica if I can, but this is hard for
me to implement.
Working through a few examples, I distilled things down to the
following snippet of code.
It puts a point on the function y = x^2 and allows the point to be
dragged along it.
f0[x_] := x^2;
DynamicModule[{p = {1, 1}},
loc := Locator[Dynamic[p, (p = {#[[1]], f0[#[[1]]]}) &]];
Show[{Plot[f0[x], {x, -10, 10}], Graphics[{loc}]},
PlotRange -> {{-4, 4}, {-1, 10}},
AspectRatio -> 1]
]
I would be grateful for a few things...
A) a little help on exactly how this works...!
B) changing the display of the locator to a point on the function
C) displaying the coordinate of the point
I appreciate the input given by members of this group.
Sorry for the trivial question, but it sure would help with a lot of
things I am trying to teach at the junior/high school level.
Tom