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Re: st: RE: sum in nonlinear equations


From   "Andreas Aschbacher" <aa_surf@gmx.at>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: sum in nonlinear equations
Date   Tue, 30 Mar 2004 13:39:08 +0200 (MEST)

>thanks Stephen and nick I 'll try with egen function
aa

How about something along the following lines? (untested!!)
> 
> Instead of 
> 
> gen `yh'= exp($A) + sum(from n =1 to 34)[n*cos($B)+ (n-1)*tan($B)] -2 in
> 1
> 
> try
> 
> tempvar X
> egen `X' = (_n<=34)*sum( _n*cos($B) + _n-1*tan($B) )
> gen `yh'= exp($A) + `X' -2 in 1
> 
> Assuming your data set has at least 34 obs in it, the idea is to use the
> egen to calculate the sum 
> 
> Stephen
> -------------------------------------------------------------
> Professor Stephen P. Jenkins <stephenj@essex.ac.uk>
> Institute for Social and Economic Research
> <a
href="http://www.ntsearch.com/search.php?q=University&v=55";>University</a> of Essex, Colchester CO4 3SQ, U.K.
> Tel: +44 1206 873374.  Fax: +44 1206 873151.
> http://www.iser.essex.ac.uk   
> 
> 
> > -----Original Message-----
> > From: owner-statalist@hsphsun2.harvard.edu 
> > [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of 
> > Andreas Aschbacher
> > Sent: 30 March 2004 09:37
> > To: statalist@hsphsun2.harvard.edu
> > Subject: st: sum in nonlinear equations
> > 
> > 
> > Dear fellows !
> > is there apossibility to write line *9* in Stata-code - 
> > I have written it in pseudocode,please look at line 9 
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > . capture program drop nlfaq
> > 
> > . program nlfaq
> >   1.    if "`1'" == "?" {
> >   2.       global S_1 " A B C"
> >   3.       global A=1
> >   4.       global B=1
> >   5.       global C=1
> >   6.       exit
> >   7.    }
> >   8.    tempvar yh  
> >   9.    gen `yh'= exp($A) + sum(from n =1 to 34)[n*cos($B)+ 
> > (n-1)*tan($B)] -
> > 2 in 1
> >  10.    replace `yh'= $A/$B +$C^2-log($B) in 2
> >  11.    replace `yh'= $A/($A+$B+$C)- sin($C) in 3
> >  12.    replace `1' = `yh'
> >  13.    
> > . end
> > 
> > . nl faq y ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > this would be very necessary for me because I could 
> > deconvolute with Stata using modified Simpsonrule for 
> > computing integrals. using LevenbergMarquardt with Stata is 
> > possible in physics,convolution- computing is very easy 
> > too,the way back namely deconvolution would be possible too 
> > if I could compute this sum
> > 
> > any help would be appreciated very much
> > andreas aschbacher,greetings to all fanatic Stata users in the world
> > 
> > -- 
> > +++ NEU bei GMX und erstmalig in Deutschland: TÜV-geprüfter 
> > Virenschutz 
> > +++ +++
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> > http://www.gmx.net/virenschutz
> > 
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> > 
> 
> 
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-- 
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