Solve system of equations by symbolic toolbox

Hi, I'm write a program to solve a system of equations :

clc

syms L Pg1 Pg2 Pg3 Pg4 teta1 teta2 teta3 lamda1 lamda2 lamda3 lamda4 lamda5 M1 M2 M3 P12 P13 P23 ;

 % Lagrange funtion
 L = (7.5*Pg1+6*285+14*Pg3+10*Pg4) + lamda1*(-1000*teta1+500*teta2+500*teta3-(Pg1+285)...
      +50)+ lamda2*(500*teta1-1500*teta2+1000*teta3-Pg3+60) +....
      lamda3*(500*teta1+1000*teta2-1500-Pg4+300)+.....
      lamda4*(teta1-0) + M1*(100/0.2 * (teta1-teta2)-126)+M2*(100/0.1 * (teta2-teta3)-130) + M3*(100/0.2*(teta1-teta3)-250);

 eq1=diff(L,Pg1)
 eq3=diff(L,Pg3)
 eq4=diff(L,Pg4)
 eq5=diff(L,teta1)
 eq6=diff(L,teta2)
 eq7=diff(L,teta3)
 eq8=diff(L,lamda1)
 eq9=diff(L,lamda2)
 eq10=diff(L,lamda3)
 eq11=diff(L,lamda4)
 eq13=diff(L,M1)
 eq14=diff(L,M2)
 eq15=diff(L,M3)
[Pg1 Pg3 Pg4 teta1 teta2 teta3 lamda1 lamda2 lamda3 lamda4 M1 M2 M3]= solve (eq1,eq3,eq4,eq5,eq6,eq7,eq8,eq9,eq10,eq11,eq13,eq14,eq15)

In command window show: Warning: 12 equations in 1 variables. > In solve>mupadSolve at 206 In solve at 93 In opf at 23 Warning: Explicit solution could not be found. > In solve at 98 In opf at 23

Pg1 =

[ empty sym ]

Pg3 =

     []

Pg4 =

     []

teta1 =

     []

teta2 =

     []

teta3 =

     []

lamda1 =

     []

lamda2 =

     []

lamda3 =

     []

lamda4 =

     []

M1 =

     []

M2 =

     []

M3 =

     []

Can you tell me the solution for it ? Thank you very much !!!!

Answer 1

[Roger Stafford]

You should tell 'solve' what variables are to be regarded as the unknowns. See the documentation at:

   http://www.mathworks.com/help/symbolic/solve.html

Look at the form:

   [y1,...,yN] = solve(eqns,vars)

where 'vars' gives the list of unknowns. Their number should match the number of outputs.

[ve ro]

Thank you very much !!!