The Implicit Phase-Fitted and Amplification-Fitted Four-Point Block Methods for Oscillatory First-Order Problems

This study introduces a family of implicit four-point block methods for solving first-order initial value problems (IVPs) with oscillatory solutions. In addition to an eighth-order block method, amplification-fitted and phase-fitted implicit block methods are also derived. The methods are implemented in a predictor–corrector framework, where the predictor is a four-point explicit block method constructed with the corresponding properties. A comprehensive stability analysis is carried out to assess the robustness of the proposed approaches. Comparative evaluations with existing methods demonstrate the superior efficiency of the new algorithms. Numerical experiments further confirm that the proposed techniques provide significant improvements over traditional methods, particularly for oscillatory IVPs.