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Re: evaluating functions and displaying results numerically

  • To: mathgroup at smc.vnet.net
  • Subject: [mg126225] Re: evaluating functions and displaying results numerically
  • From: Eduardo Fontana <prof.eduardofontana at gmail.com>
  • Date: Thu, 26 Apr 2012 05:26:30 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <7BB0E96E72E84E41B24A1FF8ED13F5E6299A6B60A7@IE2RD2XVS581.red002.local>

Dear all
Thanks to all suggestions sent through the group or individually.
The major problem with the code was repeated use of the same variable name in two instances of the code. The problem was fixed
Thats what happens when you join to pieces of code and are in a hurry.
But besides that thanks for those who suggested modifications to run the code much faster. It was very instructive.
regards
Eduardo Fontana, PhD
Professor Titular
Dep. de Eletr=F4nica e Sistemas
UFPE - Centro de Tecnologia e Geoci=EAncias
Bloco A, Sala 421 Recife - PE 50.740-550
Skype: edu.fontana
Phones: +5581-21267792, +5511-30424021
http://www.ufpe.br/fontana

On Apr 25, 2012, at 6:13 AM, Alexei Boulbitch wrote:

> thanks for the replies. I can go along with all your explanations for the Sin function, even though I havent had this interpretation of results from Mathematica before. I never had to use the N option before. What about my second enquire, reproduced below:
> In another instance, I have a summation of about 1000 terms defined as
> a function of 3 arguments. When I use numerical arguments to calculate the summation, instead of
> Mathematica calculating a numerical result it generates a symbolic
> output with all 1000 terms.
> It doesnt make sense that Mathematica chooses to do the whole thing symbolically. I have made similar calculations before, and Mathematica performed the calculation numerically. I presume that I have enabled some sort of symbolic calculation mode, but I cannot figure out where. I am attaching a a link to a pdf file showing a image of the generated result for my function called "Absorption". The other functions called by Absorption are defined prior to the definition of Absorption. I just want to show the type of result generated. Also, If I want to plot my function Absorption relative to one of the arguments, Mathematica just doesnt plot it.
> Best regards
> The output image is in the google docs file below
> https://docs.google.com/open?id=0Bw08G8QtolpXUDBnQUswdXUyVE0
> 
> 
> It looks possible that you have some function or variable in your sum that has not been defined before and, therefore, Mathematica treats the whole thing analytically.
> From the fragment you showed in the link it was difficult to see which one it could be. May be Ref?
> If you write your functions directly in the post, it will be easier to help you.
> 
> Have fun, Alexei
> 
> Alexei BOULBITCH, Dr., habil.
> IEE S.A.
> ZAE Weiergewan,
> 11, rue Edmond Reuter,
> L-5326 Contern, LUXEMBOURG
> 
> Office phone :  +352-2454-2566
> Office fax:       +352-2454-3566
> mobile phone:  +49 151 52 40 66 44
> 
> e-mail: alexei.boulbitch at iee.lu
> 



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