How can I use isqurvefit or fminsearch to have my coefficient of the function?
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Parham Babakhani Dehkordi
on 23 Apr 2015
Commented: Matt J
on 23 Apr 2015
Hi everyone,
I have the following function, how can I get the value of A,B and n by curve fitting, I tried but I was not successful.
Initial guesses for:
A=0.0005; B=0.14; n=2
y=[7.754e-05 6.825e-05 6.2156e-05 5.9374e-05 5.803e-05 5.3958e-05 5.1747e-05 4.9142e-05 8.2671e-05 7.7143e-05];
x=[0.592 0.652 0.693 0.726 0.751 0.772 0.790 0.820 0.452 0.525];
y=A+B*(x)^n;
Thanks in advance
Accepted Answer
Star Strider
on 23 Apr 2015
This works with lsqcurvefit:
y=[7.754e-05 6.825e-05 6.2156e-05 5.9374e-05 5.803e-05 5.3958e-05 5.1747e-05 4.9142e-05 8.2671e-05 7.7143e-05];
x=[0.592 0.652 0.693 0.726 0.751 0.772 0.790 0.820 0.452 0.525];
[x,ix] = sort(x);
y = y(ix);
% MAPPING: b(1) = A, b(2) = B, b(3) = n
f = @(b,x) b(1) + b(2).*x.^b(3);
B0 = [5E-4, 0.14, 2];
Prms = lsqcurvefit(f, B0, x, y);
figure(1)
plot(x, y, 'bp')
hold on
plot(x, f(Prms,x), '-r')
hold off
grid
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