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From: weemba@brahms.BERKELEY.EDU (Matthew P. Wiener)
Newsgroups: net.math,net.micro,net.micro.pc
Subject: Re: simplex algorithsm for curve fitting---any disadvantage ??
Message-ID: <11800@ucbvax.BERKELEY.EDU>
Date: Tue, 11-Feb-86 09:29:53 EST
Article-I.D.: ucbvax.11800
Posted: Tue Feb 11 09:29:53 1986
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References: <1217@princeton.UUCP>
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In article <1217@princeton.UUCP> wei@princeton.UUCP (P Wei) writes:
>I recently ported the curve fitting program, listed on BYTE 1984 May p.340,
>onto ibmpc using TURBO Pascal.
>The authors claimed that the program could fit *any* equation with *any*
>number of parameters and variables to experimental data.
>Now, I am wondering if there is any disvantage or potential problems in this
>algorithsm ???  (Up to now, we haven't met any problem yet--- Is it panacea??
>Thanks in advance .
>HP Wei (wei@princeton)

I don't know the algorithm, but the claim is garbage.  It is impossible to
fit for a,b,c,d from data points to the function y=a*exp(b*x)+c*exp(d*x).
The fitting process here is completely unstable.  (I believe this example
is due to Wilkinson in the late 1950s.)

ucbvax!brahms!weemba	Matthew P Wiener/UCB Math Dept/Berkeley CA 94720