Solution of ordinary differential equations using Fifth-order Runge–Kutta method with adaptive step. User defines initial equation coefficients, a Cauchy problem (initial value problem), segment limits and calculations precision. Program converts equation to the system of equations and starts evaluation with the Fifth-order Runge–Kutta method. Algorithm automatically choose the optimal step of the iterations in respect to the specified accuracy. After calculations program represents the graphs of numeric solution using cubic splines interpolation.