"Not enough input arguments"

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Claudia
Claudia on 17 Jun 2015
Answered: Torsten on 17 Jun 2015
Hey there!
I am trying solve two equations with fsolve but it is not working propertly. There is always the same error popping up. Could somebody tell me why? That would be great.
function x = start
%Berechnung mit Shield und Al2O3 T2_b
x0=[1700,1400];
x=fsolve(@eqns,x0);
end
function fcns=eqns(x)
T_1=x(1); T_2=x(2);
H=0.30; %[m] r1=0.15; %[m] r2=0.25; %[m] r3=0.40; %[m] T_in=1873; %[K] T_inf=298; %[K] k_al2o3=9; %[W/m*K] k_air=0.026; %[W/m*K] k_xe=0.0054; %[W/m*K] u= 0.08; %[m/s]-ANNAHME!!! v=158*10^-7; %[m^2/s] v_xe=86.6*10^-6 %[m^2/s a=20*10^-6; %[m^2/s] e=0.5 %Annahme!!!!!!! sig=5.67*10^-8 %[W/m^2*K^4]
Re=u*H/v; Pr=v/a; Nu=0.332*Re^(1/2)*Pr^(1/3);
h_out=Nu*k_air/H; h_rad=e*sig*(T_1^2+T_2^2)*(T_1+T_2)
Lc=(2*[log(r3/r2)]^(4/3))/((r2^(-3/5)+r3^(-3/5))^5/3) Rac= (g*beta)/(v_xe*alpha)*(T_1-T_2)*Lc %Rayleigh number k_eff=k_xe*0.386*(Pr/(0.861+Pr))^(1/4)*Rac^(1/4)
Rtot=log(r2/r1)/(2*pi*H*k_al2o3)+1/(h_out*2*r3*pi*H)+((log(r3/r2)/(2*pi*H*k_eff))*1/(h_rad*2*pi*H*r2))/((log(r3/r2)/(2*pi*H*k_eff))+1/(h_rad*2*pi*H*r2))
fcns(1)=h_out*r3*(T_2-T_inf)-((T_in-T_1)/log(r2/r1)); fcns(2)=(T_in-T_inf)/Rtot-h_out*2*pi*r3*(T_2-T_inf);
end
thank you a lot
Best Claudia

Accepted Answer

Ingrid
Ingrid on 17 Jun 2015
without looking at your own defined function but try this as it is the correct syntax for anonymous function definition
x=fsolve(@(x) eqns(x),x0);

More Answers (1)

Torsten
Torsten on 17 Jun 2015
I guess x0 must be a column vector:
x0=[1700;1400];
x=fsolve(@eqns,x0);
Best wishes
Torsten.

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