DAE system

*To*: mathgroup at smc.vnet.net*Subject*: [mg104174] DAE system*From*: rosenm <rosenm at mail.bg>*Date*: Thu, 22 Oct 2009 02:17:01 -0400 (EDT)

Dear colleagues, can you help me to solve the following system of differential-algebraic equations, wich describes pendulum swinging: L = 1; m = 1; Te = 10; g = 9.81; sol = NDSolve[{m*x''[t] == -x[t]*F[t]/L , m*y''[t] == -y[t]*F[t]/L - m*g, (x[t])^2 + (y[t])^2 - L^2 == 0, x[0] == 0, x'[0] == 1, y[0] == -L, y'[0] == 0, F[0] == 10.81}, {x, y, F}, {t, 0, Te}]; Thanks