详细
Currently, there are more than 30 different definitions of the fractional derivative, and their number continues to grow. Some of them are just “mind games”, but others are introduced to solve serious mathematical problems. In this paper, a new definition of the fractional order derivative is given, based on generalization of the Jacobi polynomial differentiation formula. This made it possible to introduce a scale of orthogonal polynomial systems whose closures are Sobolev spaces. The use of these derivatives made it possible to set the problem of solving singular integrodifferential equations with a Cauchy kernel on an open circuit. The existence and uniqueness of the solution of such equations is proved, and the Galerkin method for their approximate solution is substantiated. The convergence of the method is proved, and estimates of the error of approximate solutions are obtained.