A RUNGE-KUTTA-FEHLBERG CODE FOR THE COMPLEX PLANE: COMPARING WITH SIMILAR CODES BY APPLYING TO POLYTROPIC MODELS

In this paper, we modify the Runge-Kutta-Fehlberg code of fourth and fifth order with the purpose of solving initial value problems established on ordinary differential equations involving complex-valued functions of one complex variable, which are allowed to have high complexity in their definition, when integration along prescribed complex paths is required. Such initial value problems arise in certain astrophysical issues, like the polytropic models, applied to polytropic stars, and the general-relativistic polytropic models, applied to neutron stars. Comparison with similar codes is made by applying to these models.