Why does solve function return an empty value in a for cycle?

Question

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for i=1:N
    syms Tout
    sol=solve (energy_balance,Tout,'Real',true, 'IgnoreAnalyticConstraints',true);
    T_gp_out(i)=double(sol);
end

Solve function returns an empty value at the second iteration of the for cycle which i am using.

When the solve function is run separately outside the for cycle it returns a real value.

I can't understand what is going wrong when all inputs and syntax are correct.

Should I define a syms vector function outside the for cycle?

Can someone help me?

Thanks in advance.

Giorgio Ceresoli

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Giorgio Ceresoli 2020-5-29

在 MATLAB Online 中打开

energy_balance= Q_rad(i)+Q_conv(i)+n_CO2_in*h_CO2_in+n_CaO_in*h_CaO_in+n_CaCO3_in*h_CaCO3_in == n_CO2_out*(h_f_CO2+a_CO2*(Tout-T_ref)+b_CO2/2*(Tout^2-T_ref^2)+c_CO2/3*(Tout^3-T_ref^3))+n_CaO_out*(h_f_CaO+a_CaO*(Tout-T_ref)+b_CaO/2*(Tout^2-T_ref^2)+c_CaO/3*(Tout^3-T_ref^3))+n_CaCO3_out*(h_f_CaCO3+a_CaCO3*(Tout-T_ref)+b_CaCO3/2*(Tout^2-T_ref^2)+c_CaCO3/3*(Tout^3-T_ref^3));