I can confirm this behavior (see code to reproduce at the bottom). Unfortunately, it also affects parallel processing: if you try to perform a large number of fits in parallel, using a 'parfor' loop, the resulting cfit objects are "broken" in the way described by Kai.
Unless I've missed something, I'd consider this a bug. I've filed a Service Request (ID: 1-NE8ATH) with TMW. I'll get back to this thread when I hear back.
As a workaround, you could try manually evaluting the fit's anonymous function, and using the coeffvalues() function to retrieve the coefficients from the cfit object (that does work fine).
- Onno
Code to reproduce the issue:
data_x = 1:50;
data_y = (2.* data_x) + randn(size(data_x)) + 5;
figure;
plot(data_x, data_y, '.b');
title('Original data');
model = @(A, B, x) A.*x + B;
ftype = fittype(model);
fopt = fitoptions(ftype);
fopt.StartPoint = [1 1];
f = fit(data_x(:), data_y(:), ftype, fopt);
figure;
hold on;
plot(data_x, data_y, '.b');
plot(f, '-r');
hold off;
title('Fitted data');
save('fit.mat', 'f');
clear('f');
load('fit.mat');
figure;
hold on;
plot(data_x, data_y, '.b');
plot(f, '-r');
hold off;
title('Fitted data (fit loaded from disk)');
