How to cite:

Shepherd, S. G. (2014), Altitude-adjusted corrected geomagnetic coordinates: 
Definition and functional approximations, J. Geophys. Res. Space Physics, 119, 
7501–7521, doi:10.1002/2014JA020264.

v2.7 Changes

Features:

+ 20220705 added a feature to 'lock' AACGM-v2 date and time in order to
           significantly speed up calculations that constantly check to see if
           the date/time has changed in order to load new coefficients. Adding
           the HMB, for instance, does this check and the date function is
           called several times for each check, causing it to run ~3x slower
           than it did before AACGM-v2 introduced a date/time feature.

           A member was added to the AACGM-v2 date/time structure to indicate
           the status of the 'lock' and is accessed by these three new
           functions:

           int AACGM_v2_Lock(void);   /* lock AACGM-v2 date/time so no check */
           int AACGM_v2_Unlock(void); /* unlock AACGM-v2 date/time [default] */
           int AACGM_v2_Locked(void); /* query status locked flag */

+ 20230807 added functions to igrflib.c in order to perform conversions to and
           and from eccentric dipole coordinates, with corresponding MLT
           functions.

           geod2ecdip    - convert from geodetic to eccentric dipole coordinates
           ecdip2geod    - convert from eccentric dipole to geodetic coordinates
           ecdip_mlt     - compute MLT of eccentric dipole longitude
           inv_ecdip_mlt - compute eccentric dipole longitude of MLT
           ecdip_mlt_ref - reference eccentric dipole longitude for MLT

+ 20230807 moved the single function dayno() from genmag.c to rtime.c in order
           to remove dependency on aacgm library. The files genmag.c and
           genmag.h have been removed.

+ 20241122 added AACGM-v2 coefficients derived using IGRF14 model.
           added file magmodel_1590-2025.txt which contains GUFM1 and IGRF14
                 coefficients
           changed error message in aacgmlib_v2.c for date/time out of bounds

Bug fixes:

  Fixed integer division in rtime.c for function TimeYMDHMSToJulian resulting
    in times being set to start of the day.