Failure in initial user-supplied objective function evaluation. LSQCURVEFIT cannot continue.

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RuiQi
RuiQi on 7 Feb 2017
Commented: shariq khan on 18 Nov 2018
My code below generates the following error. I have been stuck at it and Im not sure why. It works for an exponential version.
x = load('depth-0.txt');
y = load('mean-0.txt');
F = @(p,x) (p(1) + p(2)*(x*x));
x0 = [-1 1];
[p,resnorm] = lsqcurvefit(F, x0, x, y);
estimate_x = 1:0.1:100;
estimate_y = (p(1) + p(2)*(estimate_x*estimate_x));
plot(estimate_x, estimate_y,'-','LineWidth',2);
Error using * Inner matrix dimensions must agree.
Error in @(p,x)(p(1)+p(2)*(x*x))
Error in lsqcurvefit (line 199) initVals.F = feval(funfcn_x_xdata{3},xCurrent,XDATA,varargin{:});
Caused by: Failure in initial user-supplied objective function evaluation. LSQCURVEFIT cannot continue.

Accepted Answer

Walter Roberson
Walter Roberson on 7 Feb 2017
F = @(p,x) (p(1) + p(2).*(x.*x));
The parameter you are describing as x will be a matrix. The * operator in MATLAB is algebraic matrix multiplication from linear algebra, which requires that the number of columns of the array on the left hand side be equal to the number of rows of the array on the right hand side of the * operator. With x * x the only way that could happen is if x was square.
The .* operator is element-by-element multiplication.
  2 Comments
shariq khan
shariq khan on 18 Nov 2018
x0 = [1,1,1e-9];
lb = [-inf,-inf,-inf];
ub = [inf,inf,inf];
fun = @(x) x(1) + x(2).*exp(-t.*x(3));
vmut_obtained = lsqcurvefit(fun,x0,t,vmut,lb,ub);
couldnt upload data set, as it is 1x157 vector
I get similar error for this function .any suggestion?

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