Re: Constraining a Location to Move Along a Plot in a Manipulate

*To*: mathgroup at smc.vnet.net*Subject*: [mg127779] Re: Constraining a Location to Move Along a Plot in a Manipulate*From*: Bob Hanlon <hanlonr357 at gmail.com>*Date*: Wed, 22 Aug 2012 02:25:19 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <20120821013043.F31B7684F@smc.vnet.net>

Manipulate[ Module[{f, m, b, xmin = -5, xmax = 5}, f[x_] := (m*x + b /. Solve[{ pt1[[2]] == m*pt1[[1]] + b, pt2[[2]] == m*pt2[[1]] + b}, {m, b}][[1]]); Graphics[{ Line[{{xmin, f[xmin]}, {xmax, f[xmax]}}], AbsolutePointSize[8], Red, Tooltip[Point[{x, f[x]}], {x, f[x]}], Blue, Tooltip[Point[ {InverseFunction[f][y], y}], {InverseFunction[f][y], y}]}, Frame -> True, Axes -> False, PlotRange -> {{xmin, xmax}, {-5, 5}}]], {{x, -1, Style["x", Red, Bold, 12]}, -5, 5, 0.1, Appearance -> "Labeled"}, {{y, 1, Style["y", Blue, Bold, 12]}, -5, 5, 0.1, Appearance -> "Labeled"}, {{pt1, {-4, -4}}, Locator}, {{pt2, {4, 4}}, Locator}] Bob Hanlon On Mon, Aug 20, 2012 at 9:30 PM, Gregory Lypny <gregory.lypny at videotron.ca> wrote: > Hello everyone, > > Awhile back, participants on this forum kindly showed me how to constrain a locator to move along a curve by using DynamicModule[...], an example of which is in the Help Centre. But I can't figure out how to pull this off in a Manipulate,where I'm guessing that the locator would be a control. Say I have a simple Manipulate that plots a line, y = mx + b, where m is control for changing the slope. I would also like to have a locator that users can slide up and down the line in lieu of a slider control that draws a point on the line. > > Regards, > > Gregory >

**References**:**Constraining a Location to Move Along a Plot in a Manipulate***From:*Gregory Lypny <gregory.lypny@videotron.ca>