Variable-order fractional calculus: A change of perspective

Several approaches to the formulation of a fractional theory calculus "variable order" have appeared in literature over years. Unfortunately, most these proposals lack rigorous mathematical framework. We consider an alternative view on problem, originally proposed by G. Scarpi early seventies, based naive modification representation Laplace domain standard kernels functions involved (constant-order) calculus. frame Scarpi's ideas within recent General Fractional Derivatives and Integrals, that mostly rely Sonine condition, investigate main properties emerging variable-order operators. Then, taking advantage powerful easy-to-use numerical methods for inversion transforms defined domain, we discuss some practical applications integral derivative.