Symbolic calculation question.

Hi,

i was been working in the longitudinal aircraft stability with these equations

i have 2 equations (DCmcgDAlfa and Cmcg) and 2 unknowns (Clt and Xcg) and i use this comand to solve the problem:

syms Clw Xcg

DCmcgDClw=((Xcg-Xca)/Cw)+((Clw*Za)/Cw)*((2/(pi*At*e))-(1/aw))+DCmfnClw+((2*Clt*at*Ht*St)/(pi*At*e*aw*Cw*Sw*Nt))*(1-DEpsilonDAlfa)-((at*St*Nt*(Lt-(Xcg-Xca)))/(aw*Sw*Cw))*(1-DEpsilonDAlfa);

Cmcg=((Xcg-Xca)/Cw)*Clw+(Clw^2)*((1/(pi*Aw*e))-(1/(2*aw)))*(Za/Cw)+Cmcaw+Cmfn+Cmcat*((St*Ct*Nt)/(Sw*Cw))+((St*Ht*Nt)/(Sw*Cw))*(Cdt+((Clt^2)/(pi*At*e)))-((Clt*Nt*(Lt-(Xcg-Xca)))/(Cw*Sw))

vars=[Xcg,Clt];

Eqn=[DCmcgDClw==0,Cmcg==0];

res=solve(Eqn,vars);

eval(res.Xcg);

it's OK the method i use? because the results are really bad!

thank you!

Nicolas

[madhan ravi]

because the results are really bad!

Meaning ? , note usage of eval() is superfluous

[Nicolas Sposato]

hi ravi,

the results not reponse at the nature of the problem.

but my question its about the method of resolution the 2 equations with 2 unknowns, its ok?

thank you!

[darova]

why didn't you declare Clt as syms variable before equations?

syms Clt Clw Xcg

[Nicolas Sposato]

Hi, darova

yes! i forget it!, the solver works very well now!

thank you!

Nicolas.