NMinimize
- To: mathgroup at smc.vnet.net
- Subject: [mg68362] NMinimize
- From: "jour" <jour at ccr.jussieu.fr>
- Date: Wed, 2 Aug 2006 05:24:30 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Hi
I am new in this usenet group, I am a chemist in Paris working on
Molecular Magnetism and I try to optimize my experimental data to
theoretical models
I sent two hours ago my first subject to this group about
NonlinearRegress
here is the theoretical function (Debye model for heat capacity)
deb[teta_,n_,t]:= 9 n (t/teta)^3 Nintegrate[(x^4
Exp[x])/(1+Exp[x])^2,{x,0,t/teta}]
I can Table this function without problem
Table[{t, deb2[100, 3, t]}, {t, 1, 200, 5}]
but when I try to use this function in NonlinearRegress
fut = NonlinearRegress[dat,
deb2[teta, n, t],
{t}, {{teta, {10., 50.}, 0., 1000.}, {n, {1, 3}, 1, 70}}]
I get an error message
NIntegrate::"nlim" t/teta is not a valid limit of integration
Actually I have the same problem with NMinimize
nmin = NMinimize[{Sum[(deb2[teta,n, dat[[i,1]]] - dat[[i, 2]])^2, {i,
Length[dat]}], 1 = n = 80 && 1
= teta = 300 }, {n, teta}, Method ->
"DifferentialEvolution"]
I get the following message error
NIntegrate::"nlim" x = 6.6778/tetais not a valid limit of integration
There is a tiny improvement because Mathematica gives a numerical
value to t. But in both approaches Mathematica does not give any
numerical value to the parameters
I get the same kind of problem if the theoretical function is obtained
by numerical diagonalization of matrices where MATHEMATICA try to
diagonalize the matrix without numerical value
Is there any way to solve these kind of problems ?
I would be very grateful if somebody could help me on this problem
best regards
Yves