how to solve non-linear equations

syms w(0),w(1),w(2)
exp1=(w(0)^2+w(1)^2+w(2)^2)-A0;
exp2=(2*w(1)*(w(0)+w(2)))-A1;
exp3=(2*w(0)*w(2))-A2
sol=solve(exp1,exp2,exp3);
sol.w(0);
sol.w(1);
sol.w(2);

error message saying

"Error using ==> syms
Not a valid variable name".

please help me

Answer 1

[Walter Roberson]

You cannot syms() a subscripted variable.

If you have a new enough MATLAB (R2012a or later), you can syms() a function giving a dummy variable name but not a number. For example

syms w(t)

If you have a new enough MATLAB (R2011b, maybe R2011a), you can sym() a vector or array of symbols into existence. Note this is sym and not syms:

w = sym('w', [1 3]);

This would create w(1), w(2), w(3) . Note it would not create w(0), which would be an invalid array subscript. 0 can be used as a function argument to a symbolic function, but functions do not declare individual symbols for the function values.

I suggest you change your variable names to not be subscripted:

syms w0 w1 w2
exp1=(w0^2+w1^2+w2^2)-A0;
exp2=(2*w1*(w0+w2))-A1;
exp3=(2*w0*w2)-A2
sol=solve(exp1,exp2,exp3);
sol.w0;
sol.w1;
sol.w2;

Answer 2

[Muruganandham Subramanian]

you can't give variable name like w(0),w(1),w(2)..here variable is w and 0,1,2..are maybe iterations.. so declare variable clearly..