Hi, I am new on this list and want to start a discussion if a library for solving ordinary differential equations (ODEs) would fit into boost. We are developing a lib - odeint - for such problems. odeint can be found in the sandbox: https://boost.org/svn/boost/sandbox/odeint, but the current stage is far away from being ready for release or submission. ODEs are usually solved iteratively. Therefore, we have introduced two stepper concepts, one for steppers with- and one for steppers without error estimation. At the moment some explicit solvers are implemented: Euler, RK4, Cash Karp, RK78,midpoint and Burlisch-Stoer. Here are some examples: typedef std::tr1::array< double , 3 > state_type; // define the ODE void lorenz( state_type &x , state_type &dxdt , double t ) { const double sigma = 10.0 , R = 28.0 , b = 8.0 / 3.0 dxdt[0] = sigma * ( x[1] - x[0] ); dxdt[1] = R * x[0] - x[1] - x[0] * x[2]; dxdt[2] = x[0]*x[1] - b * x[2]; } state_type x = {{ 1.0 , 0.0 , 0.0 }}; ode_step_euler< state_type > stepper; double t = 0.0; // iterate the ODE by hand with constant stepsize for( size_t oi=0 ; oi<10000 ; ++oi,t+=dt ) stepper.next_step( lorenz , x , t , 0.01 ); // integrate the ODE with constant stepsize // from t = 0.0 to t = 100.0 with dt = 0.01 // and write t and x[0] to cout integrate_const( rk4 , lorenz , 0.0 , 0.01 , x , 100.0 , cout << _1 << tab << _2[0] << "\n" ); // stepsize controller for rk5 cash-karp controlled_stepper_standard< stepper_rk5_ck< state_type > > rk5_controlled( rk5 , eps_abs, eps_rel, 1.0, 1.0); // solve the ODE with an adaptive stepsize controller size_t steps = integrate_adaptive( controlled_rk5, lorenz, x, 0.0, 10.0 , 0.01, cout << _1 << tab << _2[0] << "\n" ); Best regards, Karsten