X is a scalar or a vector. The data type of X can be datetime, timestamp or nanotimestamp
Convert X in local time zone to GMT (Greenwich Mean Time). GMT is also called UTC (Universal Time Coordinated).
The following examples were conducted in US Eastern time zone.
$ gmtime(2018.01.22 10:20:26); 2018.01.22T15:20:26 $ gmtime(2017.12.16T13:30:10.008); 2017.12.16T18:30:10.008