Manipulate and ParametricPlot Control?
- To: mathgroup at smc.vnet.net
- Subject: [mg114328] Manipulate and ParametricPlot Control?
- From: AES <siegman at stanford.edu>
- Date: Wed, 1 Dec 2010 02:11:32 -0500 (EST)
This is a "what did I do wrong" post? It's related to the
"re-virginating" thread I started recently, but quite separate (and I
think genuinely puzzling).
As a simple test file, I created a notebook (which I don't have any
more) containing the one cell
Manipulate[ Plot[x^a, {x,0,1}], {a,0,5}]
(May have had a PlotRange option also; don't recall for sure.)
Executed it; worked as expected.
Decided to set an initial value for a; as best I recall (details are
fuzzy), I edited the cell to change {a,0,5} to {{a,1},0,5} (that's what
I intended to do, anyway).
When I re-executed the cell, I got a live Manipulate that displayed a
***two-dimensional*** (2D) Control -- something I had never seen before,
but which looked exactly like the one I more recently found in the
ParametricPlot example in the Manipulate Help.
Exercising this Manipulate displayed **two** x^a curves, with values
corresponding to the H and V axes of the 2D Control. Functioned fine;
no error msgs at any time.
I made a (presumably erroneous) guess that the edited cell must have
somehow been influenced by the earlier execution of the initial,
un-edited version of the same cell (I had two implementations of the "a"
variable floating around, maybe??). So, I tried adding Removes before
the cell; tried Saving it, Quiting Mathematica, and re-opening it. The 2D
Control obstinately remained (and worked). This then led to the
re-virginating query.
I may have made a typo in the editing I noted above, but I sure as hell
did NOT change Plot to ParametricPlot. And when I try some tests now
using Plot[ {f1, f2}, ...] inside a Manipulate, I get two curves -- but
never a 2D Control.
Any ideas what went wrong here?