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MathGroup Archive 2000

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RE: Hold, HoldForm, ReleaseHold when Plotting multiple functions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg25506] RE: [mg25481] Hold, HoldForm, ReleaseHold when Plotting multiple functions
  • From: "David Park" <djmp at earthlink.net>
  • Date: Thu, 5 Oct 2000 23:50:24 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Sean,

It is difficult to understand why the first form works and the second form
generates error messages. Could you show us some of the error messages?
Could you tell us more about the nature of the bandwidth function? Is it
possible to produce a simple function which reproduces the error messages
which you could show us?

If the functions are very complicated, and time consuming to calculate, you
may want to generate InterpolatingFunctions for them first, outside of the
Plot command. Both forms of the Plot statement should work for them and you
won't redoing complicated calculations inside of the Plot statement.

Keep posting this to MathGroup. You should be able to get some help from
someone.

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/

> -----Original Message-----
> From: Ross Sean Civ AFRL/DELO [mailto:Sean.Ross at kirtland.af.mil]
To: mathgroup at smc.vnet.net
>
> Thank you for your response, but I had already tried a plain, old Evaluate
> and it is one of the forms that generates error messages, is
> slower than the
> explicit form, but eventually works.  This indicates that there is still
> some subtle difference between
>
> Plot[{bandwidth[28.5,x],
> >   bandwidth[28.7,x],
> >   bandwidth[28.9,x],
> >   bandwidth[29.1,x],
> >   bandwidth[29.3,x],
> >   bandwidth[29.5,x],
> >   bandwidth[29.7,x],
> >   bandwidth[29.9,x]},{x,140,200},
> >   PlotRange->{-5,5},PlotStyle->Array[Hue[#/9.]&,9]]
>
> 		---and---
>
> Plot[Evaluate[Map[bandwidth[#,x]&,{28.5,28.7,28.9,29.1,29.3,29.5,2
> 9.7,29.9}]
> ],{x,140,200},
>    PlotRange->{-5,5},PlotStyle->Array[Hue[#/9.]&,9]]
>
> I had assumed that the difference between these forms had something to do
> with Holds and order of execution, but you are telling me it does not.  In
> these kinds of problems, using a simple example, like a function Sin[p+x],
> does not always reveal the same things that using a complicated function
> involving root-finding does.  If you have any further light to
> shed on this
> problem, please let me know.
>
> P.S.
> I have several programming projects on indefinite hold due to
> cases where a
> certain syntax works on simple functions but not complex ones
> with multiple
> nested function calls.  This is the big problem with many of the
> examples in
> the documentation--they only work on simple, one line functions that don't
> call other user-created functions.
>
>
> Please respond directly to sean.ross at kirtland.af.mil as I no longer
> subscribe to the mathgroup.
>
> Dr. Sean Ross
>
> AFRL/DELO
> 3550 Aberdeen Ave. Building 761
> Kirtland AFB, NM 87117
>




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