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MathGroup Archive 2005

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Re: Nestwhile

  • To: mathgroup at smc.vnet.net
  • Subject: [mg57229] Re: [mg57201] Nestwhile
  • From: Pratik Desai <pdesai1 at umbc.edu>
  • Date: Sat, 21 May 2005 02:40:01 -0400 (EDT)
  • References: <EC9C79ED705B7D498CE6892836AA3CAABA6EF4@EAHQ-CSMB9.rws.ad.ea.com>
  • Sender: owner-wri-mathgroup at wolfram.com

Barthelet, Luc wrote:

>I am not sure NestWhile is really what you need here.
>
>I create a notebook for your function. There are a couple of typos in
>the function below I think. (w rather than dw?) there are also a lot of
>terms equal to 0.
>You function is d[e,dw]=... it probably needs to be d[e_,de_]:=...
>
>You can see the html version of the notebook at:
>http://www.mathematica-users.org/webMathematica/wiki/wiki.jsp?pageName=N
>otebook:functionMathgroup57201.nb
>
>and you can download the notebook at:
>http://www.mathematica-users.org/mediawiki/images/8/83/functionMathgroup
>57201.nb
>
>I suggest you upload your notebook at http://www.mathematica-users.org
>and that would give us more information to help you quickly.
>
>Cheers,
>Luc
>
>-----Original Message-----
>From: Pratik Desai [mailto:pdesai1 at umbc.edu] 
To: mathgroup at smc.vnet.net
>Sent: Friday, May 20, 2005 1:44 AM
>Subject: [mg57229] [mg57201] Nestwhile
>
>Hi,
>I am having problem with using NestWhile in a code which basically boils
>
>down to finding values for the variables (e,dw)  for which a function 
>d[e, dw] is "minimized" while one variable (e) goes up to 1. I have been
>
>using the following approach, which unfortunately loops for 1 
>iteration..There is definitely a better probably a simpler  way to do 
>this...Thanks in advance for your help
>
>Here is the attempt :
>
>d[ e, dw] =
>Abs[0. + 1143.8189785870038/((-2.0224920432639264 + 
>e)*(22.50249204326393 + e)) +
>   (e^3*(-2.3561944901923435 - 
>1.3322676295501878*^-15*w))/((-2.0224920432639264 + 
>e)*(22.50249204326393 + e)) -
>   56.548667764616276*w - (2573.5927018207585*dw)/((-2.0224920432639264 
>+ e)*(22.50249204326393 + e)) +
>   (e^2*(-73.38760438785755 + 
>56.54866776461624*dw))/((-2.0224920432639264 + e)*(22.50249204326393 + 
>e)) +
>   (e*(-407.4855111216201 + 
>1158.1167158193412*dw))/((-2.0224920432639264 + e)*(22.50249204326393 + 
>e))] +
> 8.*Abs[0. + 0./((-2.0224920432639264 + e)*(22.50249204326393 + e)) +
>    (0.*dw)/((-2.0224920432639264 + e)*(22.50249204326393 + e)) +
>    e^2*(0./((-2.0224920432639264 + e)*(22.50249204326393 + e)) + 
>(0.*dw)/((-2.0224920432639264 + e)*
>        (22.50249204326393 + e))) + e*(0. + 0./((-2.0224920432639264 + 
>e)*(22.50249204326393 + e)) +
>      (0.*dw)/((-2.0224920432639264 + e)*(22.50249204326393 + e)))] +
> Abs[0. + (e*(-107.23302924253159 - 
>7.105427357601*^-14*dw))/((-2.0224920432639264 + e)*(22.50249204326393 +
>
>e)) +
>   (e^3*(2.3561944901923453 - 
>4.440892098500626*^-16*dw))/((-2.0224920432639264 + 
>e)*(22.50249204326393 + e)) +
>   e^2*(48.25486315913923/((-2.0224920432639264 + e)*(22.50249204326393 
>+ e)) +
>     (0.*dw)/((-2.0224920432639264 + e)*(22.50249204326393 + e)))]
>
>Module[{e = 0.05, dw = 0.04}, NestWhile[{e += 0.01,dw += 0.1},
>   d[ e, dw],10^-2 <d[ e,  dw] <0&&e==1 ]; Print[dw,d[ e, dw],e]; 
>Return[d[j, e, dw], Module]]
>
>0.14
>25.415
>
>  
>
Hi Luc and Dr.Bob
As you can probably tell I am not much of a coder. Since in most cases 
(hopefully)you turn to the group as a last resort I tried to  compose 
the email as I was just stepping out and you can see the results  :-[ . 
Regardless as Luc suggested I have imported my file on wiki  Here is the 
link to the mathematica file:

http://www.mathematica-users.org/mediawiki/images/d/d4/ihb1.nb

Luc,
Actually the incrementaion is for two variables e and dw , actually 
w=wo+dw, and I already assumed the value for wo . As far as I can see 
there are no other typos

I am trying to solve the set of linear equations

kdA=r+q*dw (here d stands for the Greek symbol Capital delta)
where r and q are functions of e
So I first symbolically calculate dA then rewrite r=kdA-q*dw try to 
minimize r based on the values of e and dw. The variables corresponding 
to the minimum of the norm of r will give me the coeficients dA...that 
was the general idea anyway

Thank you for your quick response

Best regards,
Pratik

-- 
Pratik Desai
Graduate Student
UMBC
Department of Mechanical Engineering
Phone: 410 455 8134



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