I cannot figure out how to fix this error "Objective function is returning undefined values at initial point. fsolve cannot continue."

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Dominic Riepenhoff 2021-11-28

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https://ww2.mathworks.cn/matlabcentral/answers/1597869-i-cannot-figure-out-how-to-fix-this-error-objective-function-is-returning-undefined-values-at-initi

编辑： Matt J 2021-11-28

function dummyhw8 
clc
x0=[1,1,1,0.02,0,02,0.02];
x=fsolve(@fcn,x0);
disp ('Velocities are the first three values. Whereas friction is last 3.');
disp(x);
function z=fcn(x)
z(1)=x(1)-(0.64*x(2))-(0.64*x(3)); % where x1=v1 x2=v2 and x3=v3
z(2)=40-(102*x(4)*x(1)^2)-(127*x(5)*x(2)^2); % where x4=f1 x5=f2 x6=f3
z(3)=60-(102*x(4)*x(1)^2)-(127*x(6)*x(3)^2);
z(4)=1/sqrt(x(4))+2.0*log10((4.5e-4/3.7)+2.81e-5/x(1)/sqrt(x(4)));
z(5)=1/sqrt(x(5))+2.0*log10((5.625e-4/3.7)+3.52e-5/x(2)/sqrt(x(5)));
z(6)=1/sqrt(x(6))+2.0*log10((5.625e-4/3.7)+3.52e-5/x(3)/sqrt(x(6)));

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Dominic Riepenhoff 2021-11-28

Yup that did it, thanks! Prof gave us those values to guess with, so it still does not make the most sense but it works now.

Thanks again!

Dominic Riepenhoff 2021-11-28

Are there any ways (besides changing those values) to avoid this fsolve error, so that I could still use my initial guess values that are close to zero?

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