R2xyz                   Find the three rotation angles about new axes
                        in the xyz order from a rotation matrix
R2zyx                   Find the three angles about new axes in the zyx
                        order from a rotation matrix
R_EL2n_E                Find n-vector from the rotation matrix
                        (direction cosine matrix) 'R_EL'
R_EN2n_E                Find n-vector from R_E
R_Ee                    Select the axes of the coordinate frame E
along_track_distance    Compute the along-track distance from a great
                        circle arc
altitude_azimuth_distance
                        Calculate the altitude, azimuth and distance of
                        B from A
cross_track_distance    Compute the cross-track distance from a great
                        circle arc
cross_track_intersection
                        Calculate cross-track intersection
deg                     Convert angle in radians to degrees
lat_lon2n_E             Convert (geodetic) latitude and longitude to
                        n-vector
n_E2R_EN                Find the rotation matrix R_EN from n-vector
n_E2lat_lon             Convert n-vector to latitude and longitude
n_EA_E_and_n_EB_E2p_AB_E
                        Find the delta position from two positions A
                        and B
n_EA_E_and_p_AB_E2n_EB_E
                        Find position B from position A and delta
n_EB_E2p_EB_E           Convert n-vector to cartesian position vector
                        in meters
n_E_and_wa2R_EL         Find 'R_EL' from n-vector and wander azimuth
                        angle
nvctr                   nvctr: non-singular geographical position
                        calculations
p_EB_E2n_EB_E           Convert cartesian position vector in meters to
                        n-vector
rad                     Convert angle in degrees to radians.
unit                    Make input vector unit length, i.e. norm == 1
xyz2R                   Create a rotation matrix from 3 angles about
                        new axes in the xyz order.
zyx2R                   Create a rotation matrix from 3 angles about
                        new axes in the zyx order.
