- 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
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回答(1 个)
Walter Roberson
2019-1-14
编辑:Walter Roberson
2019-1-15
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 个评论
Torsten
2019-1-16
Then you should do as "lsqcurvefit" suggests: Set a larger value for the maximum number of iterations:
options.MaxIterations and/or options.MaxFunctionEvaluations
另请参阅
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