Abstract
The application of Runge–Kutta methods for solving rigid systems of ordinary differential equations and differential algebraic equations is considered. When solving such problems, the effect of reducing the order is often manifested, when, with a given accuracy, the real order of the method turns out to be lower than the classical order, which inevitably leads to increased computational costs. To avoid reducing the order, the method must have a sufficiently high stage order. However, the methods that provide the most convenient and efficient implementation have a low stage order. Therefore, the task of constructing methods that, at a low stage order, have the properties of methods of a higher stage order is relevant. This article is devoted to the construction of methods of this type. Singly diagonal-implicit, explicit methods and those inverse to the explicit ones are considered. The results of solving test problems are presented.