A robust stability criterion in the one-dimensional subdiffusion equation with Caputo–Fabrizio fractional derivative

In this paper, we present a robust stability criterion for the one-dimensional subdiffusion equation with Caputo–Fabrizio fractional derivative. The criterion is obtained by extending a concept of stability under constant-acting perturbations that is regularly applied to systems of differential equations of integer order. We assume the existence of uncertainty in the subdiffusion equation due to the effect of external sources that are represented by Fourier series whose generalized Fourier coefficients are absolutely continuous and bounded functions. The results obtained suggest that the robust stability criterion allows us to guarantee that the solution of the subdiffusion equation, as well as its Caputo–Fabrizio fractional derivative and its first partial derivative with respect to the longitudinal axis, are bounded by a constant whose value is initially established. The results obtained are illustrated numerically.