Failure in initial objective function evaluation. FSOLVE cannot continue.

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Matheus Rodrigues
评论： Star Strider 2018-2-5
Hello, i'm trying to solve a nonlinear system of equations and I saw on the web that the function I should be looking for was "fsolve" (I am a beginner MATLAB user). I created my personal function as the following:
function y = eita(x, alpha)
y(1) = 1.543*10^-5 * x + 0.57
y(2) =(44.092 / 0.89605 - x) - alpha
end
Then I opened another path to call fsolve:
fun = @eita
x0= [0,0]
sol = fsolve(fun,x0)
But something is wrong with my code and I get this command box report:
Subscripted assignment dimension mismatch.
Error in eita (line 2)
y(1) = 1.543*10^-5 * x + 0.57
Error in fsolve (line 230)
fuser = feval(funfcn{3},x,varargin{:});
Error in ha (line 3)
sol = fsolve(fun,x0)
Caused by:
Failure in initial objective function evaluation. FSOLVE cannot continue.

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采纳的回答

Star Strider
Star Strider 2018-2-5
You have to choose between coding them as:
function y = eita(x, alpha)
y(1) = 1.543E-5 * x + 0.57;
y(2) = (44.092 / 0.89605 - x) - alpha;
end
alpha = 3;
x0 = 1;
sol = fsolve(@(x)eita(x,alpha), x0)
to optimise ‘x’ with fixed ‘alpha’, or:
function y = eita(xv)
x = xv(1);
alpha = xv(2);
y(1) = 1.543E-5 * x + 0.57;
y(2) = (44.092 / 0.89605 - x) - alpha;
end
x0 = [1; 1];
sol = fsolve(@(x)eita(x), x0)
if you want to optimise both parameters.

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