“…The ideas and methods of complex analysis have proven to be very important in certain analytical methods for differential equations: for example, the Fokas method [19][20][21] relies heavily on Cauchy's theorem for deforming complex contour integrals, and the d-bar method [1,22,23] is based on using the complex d-bar derivative related to the Cauchy-Riemann equations. Some of these complex definitions and methods have recently been extended into fractional calculus, in some papers on complex methods for fractional differential equations [9,12,17] and the very recent fractionalisation of the complex d-bar derivative [18], although historically the connections between complex analysis and fractional calculus have not been deeply explored. Therefore, all indications are that complex methods will be equally useful in fractional calculus as in classical calculus, but a lot of work still needs to be done in developing this area.…”