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MathGroup Archive 2007

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Re: Dynamic 2D plotting in V6

  • To: mathgroup at smc.vnet.net
  • Subject: [mg77312] Re: [mg77195] Dynamic 2D plotting in V6
  • From: DrMajorBob <drmajorbob at bigfoot.com>
  • Date: Wed, 6 Jun 2007 07:28:28 -0400 (EDT)
  • References: <25222452.1181098193253.JavaMail.root@m35>
  • Reply-to: drmajorbob at bigfoot.com

This improves the picture somewhat:

Panel[Column[{Row[{Slider[Dynamic[h]], Dynamic[h]}],
    Dynamic[Plot[-Log[10, h], {h, 1/10^14, 1}, PlotPoints -> 10,
      MaxRecursion -> 15, PlotRange -> {{-h/10, h}, {0, 14}}]]}]]

And, to get more control, we can do this:

{low, high} = 10^-{14, 8}; (* for instance *)
Panel[Column[{Row[{Slider[Dynamic[h], {low, high}], Dynamic[h]}],
    Dynamic[Plot[-Log[10, h], {h, low, high}, PlotPoints -> 100,
      MaxRecursion -> 15,
      PlotRange -> {{-h/10, h}, {0, -Log[10, low]}},
      ImageSize -> 500]]}]]

Now I can adjust the slider to 10^-11 or so and see a smooth curve (still  
very steep) up to 14.

To think, we used to take most of the chart on faith!!

Bobby

On Tue, 05 Jun 2007 05:52:59 -0500, Todd Allen <genesplicer28 at yahoo.com> 
wrote:

> Hello All,
>
>    First, let me congratulate WRI on the release of
> Version 6....I think many of us are finding "golden
> nuggets" that make this a very fun release to have in
> our hands.
>
>    I'm an educator and have always been interested in
> finding a way to explain the concept of pH (defined as
> the free concentration of hydrogen ions in a solution)
> to my biology students.  Plotting pH graphically has
> always been out of the question because of the
> tremendous range of values that pH relies upon (from
> 1*10^-14 to 1).  When I saw that Version 6 has dynamic
> updating ability, I became excited with the
> possibility that V6 might dynamically update one or
> both axes on a graph and finally make it possible to
> show students how pH changes as you vary the hydrogen
> ion concentration.
>
>    If you have V6, please copy-paste the following
> short code and you can see how the slider bar does
> change the x-axis (in this case the hydrogen ion
> concentration) dynamically.
>
> Code:
>
> test2 = {Slider[Dynamic[h]],
>   Dynamic[Plot[-Log[10, h], {h, 1/10^14, 1},
>     PlotRange -> {{0, h}, {0, 14}}]]}
>
>
> The problem is that most of the interesting change in
> the pH value is "compressed" along the leftmost side
> of the slider so that the smooth, gradual increase in
> pH (as hydrogen levels drop) is not well illustrated.
> The graph itself looks "tied" to a pH value of 8, when
> at very low hydrogen concentrations there should be a
> nice gradual curve towards a pH of 14.
>
> Would anyone have any ideas how to solve this
> compression issue and make the graph more illustrative
> to students?
>
> Happy computing!
> Todd
>
>
> ___________________________________________________________________________________Be  =

> a better Heartthrob. Get better relationship answers from someone who 
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> http://answers.yahoo.com/dir/?link=list&sid=396545433
>
>



-- 

DrMajorBob at bigfoot.com


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