- objective. @model_1 or @model_2
- x0. init in both cases
- xdata. a(1:end-1) in both cases
- ydata. Image(1:end-1) in the first case and b(1:end-1) in the second case
- lb. zeroes in the first case and Image(1:end-1) in the second case
- ub. init*10 in the first case and zeroes in the second case
- options. opt (a struct) in the first case and zeroes in the second case
- no documented parameter . absent in the first case and opt (a struct) in the second case.
lsqcurvefit help - Field assignment to a non-structure array object
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Hi,
I am getting the error "Field assignment to a non-structure array object" in the line I call the lsqcurvefit function and I don't understand why.
I try to fit 2 different models. When I fit model_1 everything is fine. When I fit model_2 I got the error.
a, b - both vectors of size [1,41].
I have the following code:
opts = optimset('Display' ,'off');
for i=1:size(Image,1)
x(i,:) = lsqcurvefit (@model_1, init, a(1:end-1), Image(i, 1:end-1), zeros(size(init)), init*10, opts)
end
for i=1:size(Image,1)
x(i,:) = lsqcurvefit (@model_2, init, a(1:end-1), b(1:end-1), Image(i, 1:end-1), zeros(size(init)), init*10, opts)
end
Why do I get the error when I have one more entry in model_2? i.e. the vector b?
function y = model_2(p, a, b)
A = p(1);
B = p(2);
C = p(3);
D = p(4);
E = p(5);
y = A*exp(-a*C-b/D)+(1-A)*exp(-a*B).*(E*exp(-b/100)+(1-E)*exp(-b/40));
end
function y = model_1(p,a)
A = p(1);
B = p(2);
C = p(3);
y = A*exp(-B*a) + (1-A)*exp(-C*a);
end
0 Comments
Answers (1)
Walter Roberson
on 14 Jan 2019
Edited: Walter Roberson
on 15 Jan 2019
lsqcurvefit must have parameter order
Internally the code attempts to add additional fields to the struct expected in the 7th position and fails when the parameter is numeric zeroes .
16 Comments
Torsten
on 16 Jan 2019
Then you should do as "lsqcurvefit" suggests: Set a larger value for the maximum number of iterations:
options.MaxIterations and/or options.MaxFunctionEvaluations
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