Create a function using syms and use that function

You are trying to solve a non-linear simultaneous equation.

A function made of syms is converted into an anonymous function using matlabFunction

We tried to solve the nonlinear equations using fsolve by making two equations and two variables

'Non-collar arrangements with function handles are not allowed. Please use a cell array instead.' does not proceed.

Functions expressed in syms

f1 = x^{2} + y + 2

f2 = log(x) + y^{2}

Functions such as

f1_ = x(1)^{2} + x(2) + 2

f2_ = log(x(1)) + x(2)^{2}

I think I need to change it to the form, so please let me know if there is a solution.

Attached is the code below.

```
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
clear all
%%%%%%% variable declaration%%%%%%%%
x_s=cell(2,1);
R=8.3146261815324;
H_1=13423;
Tm_1=1356.35;
H_2=17936;
Tm_2=1728.15;
al_1=14259;
bl_1=0.45;
al_2=0;
bl_2=0;
as_1=6877.12;
bs_1=4.6;
as_2=-2450.1;
bs_2=1.87;
%%%%%%% variable declaration end %%%%%%%
syms dG_1 dG_2 T x dG_ex_l dG_ex_s dG_l(x,T) dG_s(x,T) x_ x_0 x_1 x_2
dG_1=H_1*((Tm_1-T)./Tm_1);
dG_2=H_2*((Tm_2-T)./Tm_2);
dG_ex_l=(1-x)*x*(al_1+bl_1*T)+(1-x)*x*(al_2+bl_2*T)*(1-2*x);
dG_ex_s=(1-x)*x*(as_1+bs_1*T)+(1-x)*x*(as_2+bs_2*T)*(1-2*x);
dG_l=x*dG_2+R*T*((1-x)*log(1-x)+x*log(x))+dG_ex_l;
dG_s=-(1-x)*dG_1+R*T*((1-x)*log(1-x)+x*log(x))+dG_ex_s;
T_aaa=1300:10:1800;
Tn=T_aaa(10);
dG_l_const_T=subs(dG_l,[x, T], [x_, Tn]);
dG_s_const_T=subs(dG_s,[x, T], [x_, Tn]);
pre_f=dG_s_const_T-dG_l_const_T;
f=matlabFunction(pre_f);
x_0 = fzero(f,[01]);%%%%%%%fsolve Initial Value Calculation
dG_l_f1=subs(dG_l,[x, T], [x_1, Tn]);
dG_s_f1=subs(dG_s,[x, T], [x_2, Tn]);
Diff_dG_l_f1 = diff(dG_l_f1,x_1);
Diff_dG_s_f1 = diff(dG_s_f1,x_2);
%%%%%%%%%%% The first of the two equations, %%%%%%%%%%%%%%
pre_f1=Diff_dG_s_f1-Diff_dG_l_f1;
f1=matlabFunction(pre_f1); %%%%%%%%%x_1 must be replaced by x_s(1) and x_2 by x_s(2)
%%%%%%%%%%% The second of the two equations, %%%%%%%%%%%%%
pre_f2 = Diff_dG_l_f1*(x_2-x_1)-dG_s_f1+dG_l_f1;
f2=matlabFunction(pre_f2);%%%%%%%%%%x_1 must be replaced by x_s(1) and x_2 by x_s(2)
[email protected](x_1, x_2)[f1;f2];
x_s = fsolve(F1_F2,x_0);% occur error
```

2022-09-20 14:23

F1_F2_s = @(x_s) F1_F2(x_s(1),x_s(2));

I solved it by adding the above code.

2022-09-20 14:23

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