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Abstract
I/O
Examples
Particulars
Required Reading
Version
Index_Entries

Abstract


   CSPICE_TIMDEF_GET retrieves the default zone/calendar/system
   definitions associated with calendar input strings.

I/O


   Given:

      item   is the is the Time subsystem parameter value to retrieve.

             [1,c1] = size(item); char = class(item)

                or

             [1,1] = size(item); cell = class(item)

             The parameters that may be requested are:

              item          Allowed Values
              ---------     --------------
              'CALENDAR'    'GREGORIAN'
                            'JULIAN'
                            'MIXED'

              'SYSTEM'      'TDB'
                            'TDT'
                            'UTC'

              'ZONE'        'EST', 'EDT', 'CST', 'CDT',
                            'MST', 'MDT', 'PST', 'PDT'
                            'UTC+HR'
                            'UTC-HR'       ( 0 <= HR < 13 )
                            'UTC+HR:MN'    ( 0 <= MN < 60 )
                            'UTC-HR:MN'

              The case of item is not significant.

   the call:

      [value] = cspice_timdef_get( item )

   returns:

      value   the value currently associated to 'item'.

              [1,1] = size(value); double = class(value)

   Any numerical results shown for this example may differ between
   platforms as the results depend on the SPICE kernels used as input
   and the machine specific arithmetic implementation.

Examples


   Example(1):

      ITEMS = { 'CALENDAR', 'SYSTEM' };

      %
      % Retrieve the time definition settings.
      %
      for i=1:numel(ITEMS)

         value = cspice_timdef_get( ITEMS(i) );
         fprintf( '%s -> %s\n',  char(ITEMS(i)), value )

      end

   MATLAB outputs:

      CALENDAR -> GREGORIAN
      SYSTEM -> UTC

   Example(2):

      ITEMS = { 'CALENDAR', 'SYSTEM' };

      %
      % Set the calendar to 'MIXED'
      %
      ITEM  = 'CALENDAR';
      VALUE = 'MIXED';

      cspice_timdef_set( ITEM, VALUE )

      %
      % Retrieve the time definition settings.
      %
      for i=1:numel(ITEMS)

         value = cspice_timdef_get( ITEMS(i) );
         fprintf( '%s -> %s\n',  char(ITEMS(i)), value )

      end

   MATLAB outputs:

      CALENDAR -> MIXED
      SYSTEM -> UTC

Particulars


   The routines cspice_timdef_get and cspice_timdef_set exist
   to allow SPICE toolkit users to alter the default interpretation
   of time strings made by the routine cspice_str2et.

   Normally, unlabeled time strings are assumed to belong to
   the Gregorian Calendar and are UTC times. However, you
   may alter the default behavior by calling cspice_timdef_set.

   Calendar
   --------

   You may set the calendar to be one of the following

   Gregorian   --- This is the calendar used daily the
                   Western Hemisphere. Leap years occur in this
                   calendar every 4 years except on centuries
                   such as 1900 that are not divisible by 400.

   Julian      --- This is the calendar that was in use prior
                   to October 15, 1582. Leap years occur every
                   4 years on the Julian Calendar (including all
                   centuries.)  October 5, 1582 on the Julian
                   calendar corresponds to October 15, 1582 of the
                   Gregorian Calendar.

   Mixed       --- This calendar uses the Julian calendar
                   for days prior to October 15, 1582 and
                   the Gregorian calendar for days on or after
                   October 15, 1582.

   To set the default calendar, select on of the above for value
   and make the following call.

      cspice_timdef_set( 'CALENDAR', value )


   System
   -------

   You may set the system used for keeping time to be UTC (default)
   TDB (barycentric dynamical time) or TDT (terrestrial dynamical
   time). Both TDB and TDT have no leapseconds. As such the time
   elapsed between any two epochs on these calendars does not depend
   upon when leapseconds occur.

   To set the default time system, select TDT, TDB or UTC for value
   and make the following call.

      cspice_timdef_set( 'SYSTEM', value )

   Note that such a call has the side effect of setting the value
   associated with ZONE to a blank.

   Zone
   -----

   You may alter the UTC system by specifying a time zone (UTC
   offset). For example you may specify that epochs are referred
   to Pacific Standard Time (PST --- UTC-7). The standard
   abbreviations for U.S. time zones are recognized:

      EST   UTC-5
      EDT   UTC-4
      CST   UTC-6
      CDT   UTC-5
      MST   UTC-7
      MDT   UTC-6
      PST   UTC-8
      PDT   UTC-7

   In addition you may specify any commercial time zone by using
   "offset" notation. This notation starts with the letters "UTC"
   followed by a + for time zones east of Greenwich and - for
   time zones west of Greenwich. This is followed by the number
   of hours to add or subtract from UTC. This is optionally followed
   by a colon ':' and the number of minutes to add or subtract (based
   on the sign that follows "UTC") to get the
   local time zone. Thus to specify the time zone of Calcutta you
   would specify the time zone to be UTC+5:30. To specify the
   time zone of Newfoundland use the time zone UTC-3:30.

   To set a default time zone, select one of the "built-in" U.S.
   zones or construct an offset as discussed above. Then make the
   call

      cspice_timdef_set( 'ZONE', value );

   If you "GET" a 'ZONE' it will either be blank, or have the
   form "UTC+/-HR[:MN]"

   Note that such a call has the side effect of setting the value
   associated with SYSTEM to a blank.

Required Reading


   For important details concerning this module's function, please refer to
   the CSPICE routine timdef_c.

   MICE.REQ
   TIMDEF.REQ

Version


   -Mice Version 1.0.1, 13-FEB-2015, EDW (JPL)

       Edited I/O section to conform to NAIF standard for Mice documentation.

   -Mice Version 1.0.0, 14-NOV-2013, EDW (JPL)

Index_Entries


   Change time software defaults.
   Time Zones
   Gregorian and Julian Calendars


Wed Apr  5 18:00:36 2017