Solve a variable coefficient differential equation in matlab IVP

Hi for Modeeling an engine I have to solve a differential equation of the form:

y1(theta doubledot) + y2(theta dot)+ theta= y3

where y1, y2 and y3 are function of theta ..assume y1-=theta square, y2= cos(theta) and y3= sin(theta)

Every thing I come across has constant coefficients in differential equation.

Also the initial conditions are theta at t(0) =0 and theta dot at t(0)=0

[Balmukund Agarwal]

got the answer guyz..Time marching method will solve it...