This calculates the tilt angle of the data. It allows for smoothing as well. It outputs the Standard tilt angle, Hyperbolic tilt angle, 2nd order tilt angle, Tilt Based Directional Derivative and the Total Derivative
Cooper,G.R.J., Cowan, D.R. 2006. Enhancing potential field data using filters based on the local phase. Computers and Geosciences,32, p.1585-1591
Ferreira, F., Souza, J., Bongiolo, A., Castro, L. (2013). Enhancement of the total horizontal gradient of magnetic anomalies using the tilt angle. GEOPHYSICS. 78. J33-J41. 10.1190/geo2011-0441.1.