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//
// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) ????-2008 - INRIA
// Copyright (C) 2010 - DIGITEO - Allan CORNET
//
// This file is distributed under the same license as the Scilab package.
//
function demo_datafit()
function y = FF(x)
// parametric function model
y = a*(x-b)+c*x.*x;
endfunction
function e = G(p, z)
// datafit external computes the error
a = p(1),
b = p(2),
c = p(3),
y = z(1),
x = z(2),
e = y - FF(x)
endfunction
// create the experimental data
X = [];
Y = [];
a = 34;
b = 12;
c = 14;
for x=0:.1:3, Y=[Y,FF(x)+100*(rand()-.5)];X=[X,x];end
Z = [Y; X];
//show the data points
my_handle = scf(100001);
clf(my_handle, "reset");
demo_viewCode(SCI + "/modules/optimization/demos/datafit/demo_datafit.sci");
plot(X, Y, "+");
l=legend(_("Experimental data"),2);
sleep(500);
// solve the non linear data fitting
[p,err] = datafit(G,Z,[3;5;10])
// show the fitting curve
drawlater()
plot(X,FF(X), "r");
delete(l);
l = legend([_("Experimental data"); _("Fitting function")],2);
drawnow();
endfunction
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