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// Check if the x0 is column matrix
function y=yth(t, x)
y = x(1)*exp(-x(2)*t)
endfunction
// we have the m measures (ti, yi):
m = 10;
tm = [0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5]';
ym = [0.79, 0.59, 0.47, 0.36, 0.29, 0.23, 0.17, 0.15, 0.12, 0.08]';
// measure weights (here all equal to 1...)
wm = ones(m,1);
// and we want to find the parameters x such that the model fits the given
// data in the least square sense:
//
// minimize f(x) = sum_i wm(i)^2 ( yth(tm(i),x) - ym(i) )^2
// initial parameters guess
x0 = [1.5 0.8];
// in the first examples, we define the function fun and dfun
// in scilab language
function y=myfun(x, tm, ym, wm)
y = wm.*( yth(tm, x) - ym )
endfunction
//Error
//lsqcurvefit: Initial Guess should be a column matrix
//at line 156 of function lsqnonlin called by :
//[xopt,resnorm,residual,exitflag,output,lambda,gradient] = lsqnonlin(myfun,x0')
[xopt,resnorm,residual,exitflag,output,lambda,gradient] = lsqnonlin(myfun,x0)
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