1. A computer program product for implementing a method for calculating rotations of a graphical object for display upon a computer system display using input from a computing input device, the computer program product comprising one or more computer hardware storage devices having computer executable instructions encoded thereon which, when executed upon one or more computer processors, perform the method comprising: accessing a stored graphical data structure comprising data defining a graphical object which is to be displayed on a computer system display device; receiving input from a computing input device, the input comprising data associated with an intended rotation of the graphical object; receiving one or more data structures comprising two rotations, A 1 and A 2 , the two rotations associated with the intended rotation of the graphical object; expressing each rotation as a composition of two reflections, each reflection having a common initial reflection for each of the rotations, such that A 1 =R 1 R and A 2 =R 2 R 1 and each reflection R j being of the form R j =2u j u j T −I; interpolating two unit vectors, u 0 and u 1 , by u s , 0<s<1, using a standard spherical interpolation on a two-dimensional unit sphere in three-dimensions; computing interpolated rotations using the formula A s =R s R; applying the computed interpolated rotations to the stored graphical data structure to realize the intended rotation; and storing an updated graphical data structure defining the graphical object with the rotations applied which is to be rendered upon the computer system display device.