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I keep getting this error (Failure in initial user-supplied objective function evaluation. FSOLVE cannot continue)

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Frenk
Frenk 2014-9-14
评论： Walter Roberson 2017-7-31
My currenct script looks like this:
function F = myfun(x)
x0 = [0.1 0.2 0.3 0.4]
x = x0
f1 = inline('1*(1 - x(1))+100*(-1*x(1)*x(2))');
f2 = inline('1*(2 - x(2))+100*(-1*x(1)*x(2)-1*x(2)*x(3))');
f3 = inline('1*(0 - x(3))+100*(1*x(1)*x(2)-1*x(2)*x(3))');
f4 = inline('1*(0 - x(4))+100*(1*x(2)*x(3))');
F = [f1(x);f2(x);f3(x);f4(x)]
options=optimset('Display','iter');
x = fsolve(@myfun,x0);
end
Still nothing seems to get this working, can anyone help me out? If i do not define my first [x] he will not run because there are not enough input arguments.
Thanks in advance!
Frenk

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采纳的回答

Matt J
Matt J 2014-9-14
编辑：Matt J 2014-9-14
The call to fsolve and the definition of myfun should take place in two separate workspaces. The function definition should look like this,
function F = myfun(x)
f1 = 1*(1 - x(1))+100*(-1*x(1)*x(2));
f2 = 1*(2 - x(2))+100*(-1*x(1)*x(2)-1*x(2)*x(3));
f3 = 1*(0 - x(3))+100*(1*x(1)*x(2)-1*x(2)*x(3));
f4 = 1*(0 - x(4))+100*(1*x(2)*x(3));
F = [f1;f2;f3;f4];
end
The call to fsolve should be in a different function and look like this,
x0 = [0.1 0.2 0.3 0.4];
options=optimset('Display','iter');
x = fsolve(@myfun,x0,options);
Notice also that there is no need to be using inline() in this situation. Moreover, unless you have a really old version of MATLAB, you should be discontinuing the use of inline() altogether and using Anonymous Functions instead.
  1 个评论
Matt J
Matt J 2014-9-14
Frenk's Comment:
Thank you for your explanation, the question has been solved and i can continue with my proceedings. I will keep in mind not using the inline command.

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更多回答（2 个）

Yahia Mounir
Yahia Mounir 2015-9-14
Hello I am trying to run the following file however it give me error undefined variable X, I attached the my file can you help with that ,
Please note if i call the function at command window with the following steps @myfun t x0=[0 0] x=(@myfun,xo) it is working and giving me the answer i need only to use the mfile to get the answer
  1 个评论
Walter Roberson
Walter Roberson 2015-9-14
Just like Matt J explained, you need to be using two different files.
File myfun.m
function F = myfun(x)
F = [2*x(1) - x(2) - exp(-x(1));
-x(1) + 2*x(2) - exp(-x(2))];
end
file myfun_driver.m
x0=[0 0];
options = optimoptions('fsolve', 'Display', 'iter'); % Option to display output
x = fsolve(@myfun,x0,options);
Then you would invoke
myfun_driver
to run the code.

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Henn
Henn 2017-7-31
My current script looks like this:
for kk=1:+1:21;
sigma=sigmastart+0.01*(kk-1)
beta1 = 0.5-alpha/sigma^2+sqrt((0.5-alpha/sigma^2)^2+2*rho/sigma^2);
beta2 = 0.5-alpha/sigma^2-sqrt((0.5-alpha/sigma^2)^2+2*rho/sigma^2);
e=0:+0.001:100;
%guesses for investment and switching thresholds
xi010=(beta1/(beta1-1))*(rho-alpha)*(H*F*rho*I)/rho;
xi120=(beta2/(beta2-1))*(rho-alpha)*(H*F/rho-S12);
xi210=(beta1/(beta1-1))*(rho-alpha)*(H*F/rho+S21);
a010=xi010^(1-beta1)/(beta1*(rho-alpha));
a120=-xi120^(1-beta2)/(beta2*(rho-alpha));
a210=xi210^(1-beta1)/(beta1*(rho-alpha));
%initial guess for operational decisions
vars0 = [a120 a210 xi120 xi210];
%specify options for fsolve
opts=optimset('fsolve');
opts=optimset(opts , 'Maxiter' , 2000 , 'Tolx' , 1e-6, 'tolfun' , 1e-6);
vars = fsolve(@fffRoinvof , vars0 , opts , beta1 , beta2 , alpha , H , F , rho , S12, S21);
and my function file looks like this
function f = fffROinvof (vars,beta1,beta2,alpha,H,F,rho,S12,S21)
a12=vars (1);
a21=vars (2);
xi12=vars (3);
xi21=vars (4);
f=zeros(4,1);
f(1)=a12*xi12^beta2+xi12/(rho-alpha)- H*F/rho-a21*xi12^beta1+S12;
f(2)=beta2*ai12*xi12^(beta1-1);
f(3)=-a21*xi21^beta1+...
1/(rho-alpha)-H*F/rho+a12*xi21^beta2-S21;
f(4)=-beta1*a21*xi21^(beta1-1)+...
1/(rho-alpha)+beta2*a12*xi21^(beta2-1);
end
However, I still get the error message when I run my script Error in Code (line 34) vars = fsolve(@fffRoinvof , vars0 , opts , beta1 , beta2 , alpha , H , F , rho , S12, S21);
Caused by: Failure in initial objective function evaluation. FSOLVE cannot continue.
  1 个评论
Walter Roberson
Walter Roberson 2017-7-31
Change
vars = fsolve(@fffRoinvof , vars0 , opts , beta1 , beta2 , alpha , H , F , rho , S12, S21);
to
vars = fsolve(@(vars) fffRoinvof(vars, beta1 , beta2 , alpha , H , F , rho , S12, S21), vars0 , opts );

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