Rohul AminThanin SitthiwiratthamMuhammad Bilal HafeezWojciech Sumelka2025-03-102025-03-102023Progress in Fractional Differentiation and Applications2356933610.18576/pfda/0902032-s2.0-85152469544https://repository.dusit.ac.th//handle/123456789/4540Variable order integrations and differentiations are the natural extensions of the corresponding usual operators. The idea was first introduced by Samko and his coauthors. Due to the importance of the said area, we consider a class of fractional integro-differential equations(FIDEs) under the variable order (VO) differentiation. Our investigation is related to numerical solution. For the said results, we utilize Haar collocation method (HCM). The concerned method has a convergence rate of order two and itself based on BroydenÕs technique. Various examples are testified by using the said techniques. Numerical interpretations are done by using Matlab. © 2023 NSP Natural Sciences Publishing Cor.Fractional calculusGauss elimination methodHaar waveletnumerical approximationArticleScopus