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MathGroup Archive 1998

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Extracting parameters from NonlinearFit



Recently I began writing a program to do a monte carlo simulation of an
NMR experiment. The whole routine is attached (I hope that works.) The
problem is this:
I perform a NonlinearFit utilizing an exponential function of the form
Exp[-a*x]. The nonlinear fit gives me back an equation, something like
1*E(-a*x). I want to extract the a parameter out of the equation and do
two things with it. Because I am performing this simulation several
(thousand) times, I want to know the standard deviation of the a
parameters. Second, I would like to get an average of the terms
(without having to use the last two lines of my code). If anyone out
there could help me out, I would greatly appreciate it; I'm really
stuck.

(PS, if you try to run my code, you may want to change the number of
iterations to 10 or so. 10000 iterations takes a couple of hours.)

Jeff Wank
Dept of Chemistry & Biochemistry
University of Colorado at Boulder
jrw@atlantis.colorado.edu
(303) 492-8085


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    values = \((a[#1, t]&)\)/@Table[i, {i, 1, n}]; \n
    newlist = \((Transpose[{t, #1}]&)\)/@values; \n
    \n (*fitting\ the\ data*) \n\n\t
    lamda1\  = \ 
      \((NonlinearFit[newlist[\([#]\)], init*Exp[\(-a\)*x], {x}, {a,
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