Symbolic solution of differential equation with several variables and constants

Hey,

I want to solve a set of differential equations by symbols, but I don't succeed. Can somebody help me out with the code? This is what I have

%1. all my variables, some of them are time variables, some are constant, Matlab 2010b gave an error -

??? Error using ==> syms at 61 Not a valid variable name.

syms h(t) l(t) rho ohm(t) A(t) Qin Cin Qout(t) Cout(t) alpha mu P(t) A(t) Rm

%2. My equations
%f1
h=f(L, rho, omega, A, Qin, Qout, Cin, Cout) + f(L,rho,ohm)*dh/dt
%f2
h=f(alpha, rho, mu, P, A, Qout, Rm)

%3. symbolic solver - I want Matlab to eliminate h from the two equations, and to write the equation in function of Qout; then I want to do the same but to solve the equation to Cout

dsolve(f1,f2,Qout) %no h in the function

or

dsolve(f1,f2,Cout) %no h in the function

I tried some things, I have the sym-toolbox but I don't advance at all? Some ideas how Matlab can do this?

Thanks a lot!

[Walter Roberson]

Which MATLAB version are you using? Using syms to declare a function is quite new, only a release or two old.

[Star Strider]

i thought ‘syms’ was fairly old. What is newer than her 2010b version is the ability to declare and use the function ‘h(t)’ etc. syntax. That is new to 2012a.