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Testing exemple in chap.33 problems


I'm currently testing the non-linear fitting in chapter 33,

I slightly modified the exemple it to accept two guessing parameters instead 
of 3, and the formula X(t)=X(0)exp(-t/Y)

With 10 values of X(t) and t.
t= 10 20 40 80 150 250 400 600 1000 1500
The X(t) values are obtained by placing x(0)=5 and Y=500 in formula to get 
perfect
data. The I place them in the program trying to find back the 5 and 500.

(sigma is calculated for each dot)

Convergence to my values cannot be obtained.

May it be the esprel and espabs (absolute err and relative err, in 
convergence.c) who cause that or is there a problem with ratio testing in 
lmiterate.c or any other
problem I might not have see.

There are no modifications exept those I mantionned, gsl-0.8 no mods in 
source lib.

Thanks
Robin Drolet
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