"Not enough input arguments"

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

Answer 1

[Ingrid]

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);

[Claudia]

Thanks a lot

Answer 2

[Torsten]

I guess x0 must be a column vector:

x0=[1700;1400];

x=fsolve(@eqns,x0);

Best wishes

Torsten.