Re: tooltip - evaluate function at point

• To: mathgroup at smc.vnet.net
• Subject: [mg98770] Re: tooltip - evaluate function at point
• From: dbreiss at gmail.com
• Date: Sat, 18 Apr 2009 03:39:47 -0400 (EDT)
• References: <gs6pjo\$h7i\$1@smc.vnet.net> <gs9ejj\$ms2\$1@smc.vnet.net>

```Hi Cristina,

The problem here seems to be that ContourPlot has built into it a
tooltip that tells you which equation the contour lines correspond
to.  This actually was what I thought was a bug in my example, but I
realize that it is a "feature" of ContourPlot.  I have to think of how
to turn that off, as that tooltip seems to preempt any other tooltip
that is imposed on the plot as I did.

....Ah, this seems to do the trick, I think, using the option
ContourLabels -> None]:

With[{plot =
ContourPlot[Arg[Gamma[x + I*y]] == 0, {x, -10, 10}, {y, -10, 10},
PlotPoints -> 20, ContourLabels -> None]},
Dynamic@Tooltip[
plot, (With[{z = Complex @@ MousePosition["Graphics"]}, {z, Gamma
[z]}])]]

Yes, if you look up the ContourLabels documentation, this is indeed
what's needed.

Does this work for you?

Best regards,

David

_______________________________________________________
On Thu, Apr 16, 2009 at 9:50 PM, Cristina <> wrote:
David,

Thank you for your help. Unfortunately, this shows the value of Gamma
at all points other than the points on the solution curves given by Arg
[Gamma[x+I*y]]==0. When the mouse goes over the points on the curve
the tooltip gives only "Arg[Gamma[x+I*y]]==0. But I am interested in
the value of Gamma precisely at the points on the curves above.

Best wishes,

Cristina

>>> <David> 04/16/09 8:09 PM >>>
Here is the start of one sort of approach.  It seems ot have some
bugginess though.  But perhaps this will get you going:

With[{plot =
ContourPlot[Arg[Gamma[x + I*y]] == 0, {x, -10, 10}, {y, -10, 10},
PlotPoints -> 20]},
Dynamic@Tooltip[
plot,
(With[{z = Complex @@ MousePosition["Graphics"]},
{z, Gamma[z]}])
]
]

I suspect that someone else will give you a more stable approach....

--David

On Apr 16, 4:18 am, "Cristina" <>
wrote:
> I would like to plot the solutions to an equation using ContourPlot and
> add a tooltip that evaluates a different function at the points on the
> solution. In particular, for the plot
>
> ContourPlot[Arg[Gamma[x + I*y]] == 0, {x, -10, 10}, {y, -10, 10}, PlotPoints -> 20]
>
> when the cursor is over a solution point I would like the ToolTip to
> display the value of Gamma at that point. Is this possible? If so, any
> suggestion is greatly appreciated.
>
> Cristina

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