# Failure in initial objective function evaluation. FSOLVE cannot continue.

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Ahmed Saleem on 2 Jan 2021
Commented: Ahmed Saleem on 2 Jan 2021
I want to use fsolve in loop so that every time 'a' change, my X(1) value change and my other values change accordingly. Can anyone help with it And Also can you plot x1 and y1? Any help would be appreciated.
function F = Sample13(X,a)
x1=X(1);
x2=X(2);
y1=X(3);
y2=X(4);
p1sat=X(5);
p2sat=X(6);
p=X(7);
t=X(8);
f1 = p1sat-(exp(16.59158 -(3643.31/(t -33.424))));
f2 = p2sat-(exp(14.25326 -(2665.54/(t -53.424))));
f3 = p - 101.325;
f4 = x1 - a;
f5 = x1 + x2 - 1;
f6 = y1 + y2 - 1;
f7 = (y1*p)-(x1*p1sat);
f8 = (y2*p)-(x2*p2sat);
F=[f1;f2;f3;f4;f5;f6;f7;f8];
end
To Run Function M using this command:
fhandle=@Sample13;
for a=1:0.05:2
X0 = [0.5,0.5,0.5,0.5,200,200,101.325,333.9];
options = optimset('display','off');
X = fsolve(fhandle,X0,options);
disp(X)
end

Mischa Kim on 2 Jan 2021
Edited: Mischa Kim on 2 Jan 2021
Ahmed, use the following:
fhandle = @Sample13;
options = optimset('display','off','Algorithm','levenberg-marquardt');
a = 1:0.05:2;
for ii = 1:numel(a)
X0 = [0.5,0.5,0.5,0.5,200,200,101.325,333.9,a(ii)];
X = fsolve(fhandle,X0,options);
disp(X)
end
function F = Sample13(X)
x1=X(1);
x2=X(2);
y1=X(3);
y2=X(4);
p1sat=X(5);
p2sat=X(6);
p=X(7);
t=X(8);
a = X(9);
f1 = p1sat-(exp(16.59158 -(3643.31/(t -33.424))));
f2 = p2sat-(exp(14.25326 -(2665.54/(t -53.424))));
f3 = p - 101.325;
f4 = x1 - a;
f5 = x1 + x2 - 1;
f6 = y1 + y2 - 1;
f7 = (y1*p)-(x1*p1sat);
f8 = (y2*p)-(x2*p2sat);
F=[f1;f2;f3;f4;f5;f6;f7;f8];
end
Essentially, you treat a as another function input.
##### 1 CommentShowHide None
Ahmed Saleem on 2 Jan 2021
Thnx mate.

R2016a

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