reshape() error in the function created by matlabFunction()

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matlabFunction() has generated for me AmplAndDers() to be used in fminunc(). The very first objective function evaluation fails:
Error using reshape
Number of elements must not change. Use [] as one of the size inputs to automatically calculate the appropriate size for that dimension.
Error in AmplAndDers (line 93)
Hess = reshape([-t2.*t3.*t4. ... .*(3.0./4.0)],[4,4]);
The signature of the function is:
function [Ampl,GradA,Hess] = AmplAndDers(C1_0,C2_0,R1_0,R2_0,w,x1,x2,x3,x4)
I call it with a w being an array. Two other outputs are returned correctly. I do not understand what does the above suggestion mean:
Use [] as one of the size inputs to automatically calculate the appropriate size for that dimension.
If I manually change the above reshape() call to end with:
...*(3.0./4.0)],[4,4,length(w)]);
the program runs OK.
How can avoid the manual intervention?
  4 Comments
Valeri Aronov
Valeri Aronov on 24 Aug 2021
Oops. The call is here:
function [x, fval] = OptimizeFilter(A0, f, x0)
options = optimoptions('fminunc','Algorithm','trust-region','SpecifyObjectiveGradient',true, HessianFcn','objective');
[x,fval,exitflag,output] = fminunc(@Target, [1,1,1,1], options)
function y = Target(x)
[aCurrent, GradW, HessW] = AmplAndDers(x0(1), x0(2), x0(3), x0(4), f, x(1), x(2), x(3), x(4));
...
end
end

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Accepted Answer

Valeri Aronov
Valeri Aronov on 3 Sep 2021
The error is known to MATLAB and will be fixed in the future

More Answers (1)

KSSV
KSSV on 21 Aug 2021
Read the documentation of reshape and understand it. The error is clear, you are trying to create extra elements than present in the array while reshaping.
Example:
A = rand(1,25) ;
B = reshae(A,5,5) ; % 5*5 = 25, no error as same elements present
C = reshape(A,6,5) ; % 6*5 = 30, error as A as 30 elements only.
  1 Comment
Valeri Aronov
Valeri Aronov on 21 Aug 2021
The body of AmplAndDers() function and the reshape() call code in it is generated by matlabFunction(). I can't see how reading the documentation of reshape() can possibly help me. And, yes, the error is clear indeed.

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