“…They have the ability to solve fractional order problems, whose solutions are difficult or sometimes impossible to obtain with other traditional methods. For new readers, we strongly recommend studying the results obtained in [ 21 , 22 , 23 , 24 , 25 , 26 ] for a clear understanding and developing a good base. However, to the best of our knowledge, the spectral method becomes difficult and sometimes fails to handle the situation when boundary conditions are given in more complicated forms such as local conditions, nonlocal m-point terminal conditions, integral type terminal conditions, and radiation boundary conditions.…”