RK4 is a MATLAB library which implements a simple Runge-Kutta solver for an initial value problem.
The rk4() function does not include any error estimator. It takes a single step at a time, requiring the user to control the step size.
The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.
RK4 is available in a C version and a C++ version and a FORTRAN77 version and a FORTRAN90 version and a MATLAB version and a Python version.
RKF45, a MATLAB library which implements the Runge-Kutta-Fehlberg ODE solver.
TEST_ODE, a MATLAB library which contains routines which define some test problems for ODE solvers.
You can go up one level to the MATLAB source codes.