Parameters estimation using lsqcurvefit
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Hi I am trying to do parameter estimation following the code prepared by Star Strider ‘Igor_Moura'. I have added several differential equations and edited the code. But it does not run. I would really appreciate it if you would help me to solve my problem. Thank you.
Always I receive the following message : Failure in initial user-supplied objective function evaluation. LSQCURVEFIT cannot
continue.
Attached the script
Please help
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Star Strider
2021-4-14
I did not see this originally, or I would have responded to it several days ago.
The code needed some tweaks (that I will let you find, referring to the ‘Igor-Moura.m’ code will make this easier). I attached it here. It now runs, and produces:
Rate Constants:
p(1) = 5.09562
p(2) = 0.02642
p(3) = 3.25429
p(4) = -0.28403
p(5) = 1.06602
p(6) = 16.32329
p(7) = 0.20617
p(8) = 3.98434
p(9) = 1.38866
p(10) = 4.19445
p(11) = -5.18517
p(12) = 0.05000
p(13) = 0.67375
p(14) = 0.22527
p(15) = -0.22388
p(16) = 12.31547
p(17) = 14.00000
p(18) = -5.37072
p(19) = 79.89868
p(20) = -0.27531
p(21) = 19.43315
p(22) = 0.88034
p(23) = 20.60852
p(24) = 2.81029
p(25) = -0.48154
p(26) = 3.54883
p(27) = 0.07324
p(28) = 2.13279
p(29) = 1.30150
p(30) = 0.24330
p(31) = 121.96400
p(32) = 2.20000
p(33) = 2.20000
Adding:
for k = 1:size(yexp,2)
subplot(8,2,k)
plot(t, yexp(:,k), 'p')
hold on
plot(tv, yfit(:,k), '-r')
hold off
title(sprintf('Column %2d',k))
end
after the ‘yfit’ assignment demonstrates that the fit is not close, however now that the code runs, you can work on fixing it so that it produces better results.
4 个评论
Mouna YAHYA
2021-4-15
Star Strider
2021-4-15
As always, my pleasure!
That is a Warning, not an error, and indicates that ode15s (necessary to run this) encountered a singularity 
at that point and could not continue. These are caused by what is essentially a division-by-0 or an exponential or similar function approaching ∞. You need to go through your code to understand where that occurred, and why. (Most times, this is related to an initial condition, or a coding error.) I do not understand what your code does, so my efforts were limited to getting it to run.
at that point and could not continue. These are caused by what is essentially a division-by-0 or an exponential or similar function approaching ∞. You need to go through your code to understand where that occurred, and why. (Most times, this is related to an initial condition, or a coding error.) I do not understand what your code does, so my efforts were limited to getting it to run. I will help as I can, however for situations such as this, you need to find the problem and then fix it.
Mouna YAHYA
2021-4-15
Star Strider
2021-4-15
As always, my pleasure!
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