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

Asked by Marios Karatiso on 15 Apr 2019
Latest activity Commented on by Marios Karatiso on 15 Apr 2019
Hello, I get the following error when trying to use fsolve:
Error in fsolve (line 218)
fuser = feval(funfcn{3},x,varargin{:});
Caused by:
Failure in initial user-supplied objective function evaluation. FSOLVE cannot continue.
It also prints the following error: Index exceeds matrix dimensions.
Can anyone see where is the error in that situation?
I call the fsolve with that line of code:
sol=fsolve(@set,[1;-1])
The function is the following:
function F=set(x)
Vcc=15;
Rth=(100/3)*10^3;
Re=10*10^3;
Rc=20*10^3;
beta_f=100;
beta_R=1;
Is=5*10^(-16);
Vt=0.025;
Voc=10;
F=[x(1)-(-Rth-Re(beta_f+1))*(Is/beta_f)*(exp(x(1)/Vt)-1)-(-Rth+beta_R*Re)*(Is/beta_f)*(exp(x(2)/Vt)-1)+Voc;
x(2)-(-Rth+Rc*beta_f)*(Is/beta_f)*(exp(x(1)/Vt)-1)-(-Rth-Rc*(beta_R+1))*(Is/beta_f)*(exp(x(2)/Vt)-1)-Vcc+Voc];
end

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1 Answer

Answer by madhan ravi
on 15 Apr 2019
Edited by madhan ravi
on 15 Apr 2019
 Accepted Answer

Note: Don't name your function set() will shadow the in-built function set().
sol=fsolve(@set1,[1,-1])
function F=set1(x)
Vcc=15;
Rth=(100/3)*10^3;
Re=10*10^3;
Rc=20*10^3;
beta_f=100;
beta_R=1;
Is=5*10^(-16);
Vt=0.025;
Voc=10;
F=[x(1)-(-Rth-Re*(beta_f+1))*(Is/beta_f)*(exp(x(1)/Vt)-1)-(-Rth+beta_R*Re)*(Is/beta_f)*(exp(x(2)/Vt)-1)+Voc;
% ^----- missed it
x(2)-(-Rth+Rc*beta_f)*(Is/beta_f)*(exp(x(1)/Vt)-1)-(-Rth-Rc*(beta_R+1))*(Is/beta_f)*(exp(x(2)/Vt)-1)-Vcc+Voc];
end
Gives:
Equation solved.
fsolve completed because the vector of function values is near zero
as measured by the default value of the function tolerance, and
the problem appears regular as measured by the gradient.
<stopping criteria details>
sol =
-11.3516
0.7520
>>