JNISpice
version 2.0.0

spice.basic
Class TDBTime

java.lang.Object
  extended by spice.basic.Time
      extended by spice.basic.TDBTime

public class TDBTime
extends Time

Class TDBTime implements time representations and provides time string parsing, conversion, and output formatting methods.

TDBTime objects are used throughout JNISpice to represent times acting as independent variables for computations. As such the role of TDBTime objects is analogous to that played by ET (also called TDB or "Barycentric Dynamical TDBTime") in the SPICE Toolkit.

The principal time string parsing method is the constructor TDBTime(String str) This constructor accepts strings having formats supported by the SPICE routine STR2ET.

The principal time string formatting method is toString(String picture) This method formats TDBTimes as strings using a format picture. The format picture specification is that supported by the SPICE routine TIMOUT.

Class TDBTime overrides class Object's toString() method, so TDBTime objects may be conveniently displayed via Java's System.out.println method. The format used by the method toString() is fixed, however.

The implementation of the TDBTime class is not part of the class' API and is subject to change. Currently the implementation uses double precision numbers to represent epochs; the implementation may later be enhanced to provide higher precision.

Version 1.0.0 21-DEC-2009 (NJB)


Constructor Summary
TDBTime(double secondsPastJ2000TDB)
          Construct a TDBTime from a double precision count of seconds past J2000 TDB.
TDBTime(java.lang.String timeString)
          Construct a TDBTime from a time string.
TDBTime(TDBTime t)
          Copy constructor: create a new TDBTime value from another.
TDBTime(Time t)
          Universal constructor: create a TDBTime from any Time instance.
 
Method Summary
 TDBTime add(Duration d)
          Add a Duration to a TDBTime.
 boolean equals(java.lang.Object obj)
          Test two TDBTimes for equality.
 double getTDBSeconds()
          Express a TDBTime as a count of TDB seconds past J2000 TDB.
 int hashCode()
          Return hash code for a TDBTime object.
 TDBTime sub(Duration d)
          Subtract a Duration from a TDBTime.
 TDBDuration sub(Time t)
          Subtract a Time instance from this TDBTime, producing a TDBDuration.
 java.lang.String toString()
          Convert a TDBTime to a formatted time string using a default picture.
 java.lang.String toString(java.lang.String picture)
          Convert a TDBTime to a formatted time string using a format picture.
 java.lang.String toUTCString(java.lang.String format, int precision)
          Convert a TDBTime to a formatted time string using a format code and an integer precision level for fractional seconds.
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 

Constructor Detail

TDBTime

public TDBTime(double secondsPastJ2000TDB)
Construct a TDBTime from a double precision count of seconds past J2000 TDB.

Note that the input is a primitive type, so no semantic checking is possible. The user must ensure that the input value has the correct reference epoch and time system.


TDBTime

public TDBTime(TDBTime t)
Copy constructor: create a new TDBTime value from another.


TDBTime

public TDBTime(Time t)
        throws SpiceException
Universal constructor: create a TDBTime from any Time instance.

This constructor performs all supported time conversions that produce a result expressed as seconds past J2000 TDB.

Throws:
SpiceException

TDBTime

public TDBTime(java.lang.String timeString)
        throws SpiceErrorException
Construct a TDBTime from a time string.

   -Procedure TDBTime (Construct TDBTime object from String)

   -Abstract

      Convert a string representing an epoch to a double precision
      value representing the number of TDB seconds past the J2000
      epoch corresponding to the input epoch.

   -Copyright

      Copyright (2003), California Institute of Technology.
      U.S. Government sponsorship acknowledged.

   -Required_Reading

      TIME

   -Keywords

      TIME

   -Brief_I/O

      VARIABLE  I/O  DESCRIPTION
      --------  ---  --------------------------------------------------
      str        I   A string representing an epoch.

      This constructor instantiates a new TDBTime object which represents
      the time designated by the input string.

   -Detailed Input

      str        is a string representing an epoch.  Virtually all common
                 calendar representations are allowed. You may specify a
                 time string belonging to any of the systems TDB, TT,
                 UTC.  Moreover, you may specify a time string relative to
                 a specific UTC based time zone.

                 The rules used in the parsing of `str' are spelled out in
                 great detail in the CSPICE routine tpartv_. The basics
                 are given in the Particulars section below.

   -Detailed Output

      This constructor instantiates a new TDBTime object which represents
      the time designated by the input string.  TDBTime objects are used
      throughout JNISpice to represent times that act as independent
      variables for computations.  As such the role of TDBTime objects
      is analogous to that played by ET (also called TDB or "Barycentric
      Dynamical TDBTime") in SPICELIB and CSPICE.

   -Files

      None.

   -Exceptions

      A SpiceErrorException is thrown if the input string cannot
      be processed.  The following conditions are diagnosed.

      1) The error SPICE(UNPARSEDTIME) is signaled if the
         string cannot be recognized as a legitimate time string.

      2) The error SPICE(TIMECONFLICT) is signaled if more than
         one time system is specified as part of the time string.

      3) The error SPICE(BADTIMESTRING) is signaled if any component
         of the time string is outside the normal range of usage.
         For example, the day January 35 is outside the normal range
         of days in January. The checks applied are spelled out in
         the CSPICE routine tcheck_.

   -Particulars

      This method creates a TDBTime object corresponding to an input
      string.  While the internal representation of a TDBTime object
      is not exposed as part of the TDBTime API, TDBTime objects play
      the same role in the JNISpice system as do Barycentric Dynamical
      TDBTime (also called TDB or ET) values do in SPICELIB and CSPICE.

      The variety of ways people have developed for representing times is
      enormous. It is unlikely that any single subroutine can accommodate
      the wide variety of custom time formats that have arisen in various
      computing contexts. However, we believe that this constructor will
      correctly interpret most time formats used throughout the planetary
      science community. For example this constructor supports ISO time
      formats, UNIX `date` output formats, VMS time formats, MS-DOS
      formats, etc.  One obvious omission from the strings recognized by
      this constructor are strings of the form

           93234.1829  or 1993234.1829

      Some readers may recognize this as the epoch that is 0.1829
      days past the beginning of the 234'th day of 1993.  However,
      many other readers may regard this interpretation as a bit
      obscure.

      Below we outline some of the rules used in the interpretation
      of strings.  A more complete discussion of the interpretation
      of strings is given in the CSPICE routine tpartv_.


      Default Behavior
      ----------------

      Consider the string

           1988 June 13, 3:29:48

      There is nothing in this string to indicate what time system
      the date and time belong to.  Moreover, there is nothing to
      indicate whether the time is based on a 24-hour clock or
      twelve hour clock.

      In the absence of such indicators, the default interpretation
      of this string is to regard the time of day to be a time on
      a 24-hour clock in the UTC time system.  The date is a date
      on the Gregorian Calendar (this is the calendar used in nearly
      all western societies).

      Labels
      ------

      If you add more information to the string, str2et can
      make a more informed interpretation of the time string.
      For example:

           1988 June 13, 3:29:48 P.M.

      is still regarded as a UTC epoch.  However, with the addition
      of the "P.M." label it is now interpreted as the same epoch
      as the unlabeled epoch 1988 June 13, 15:29:48.   Similarly

           1988 June 13, 12:29:48 A.M.

      is interpreted as

            1988 June 13, 00:29:48

      For the record: 12:00 A.M. corresponds to Midnight (00:00 on the
      24 hour clock.  12:00 P.M. corresponds to Noon. (12:00) on the
      24 hour clock.

      You may add still further indicators to the string.  For example

          1988 June 13, 3:29:48 P.M. PST

      is interpreted as an epoch in the Pacific Standard Time system.
      This is equivalent to

          1988 June 13, 07:29:48 UTC

      The following U.S. time zones are recognized.

         EST   --- Eastern Standard Time  ( UTC-5:00 )
         CST   --- Central Standard Time  ( UTC-6:00 )
         MST   --- Mountain Standard Time ( UTC-7:00 )
         PST   --- Pacific Standard Time  ( UTC-8:00 )

         EDT   --- Eastern Daylight Time  ( UTC-4:00 )
         CDT   --- Central Daylight Time  ( UTC-5:00 )
         MDT   --- Mountain Daylight Time ( UTC-6:00 )
         PDT   --- Pacific Daylight Time  ( UTC-7:00 )

      In addition any other time zone may be specified by representing its
      offset from UTC. 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 to get the local
      time zone.  Thus to specify the time zone of Calcutta (which is 5
      and 1/2 hours ahead of UTC) you would specify the time zone to be
      UTC+5:30.  To specify the time zone of Newfoundland (which is 3 and
      1/2 hours behind UTC) use the offset notation UTC-3:30.

      For the Record:  Leapseconds occur at the same time in all
      time zones.  In other words, the seconds component of a time
      string is the same for any time zone as is the seconds
      component of UTC.  Thus the following are all legitimate
      ways to represent an epoch of some event that occurred
      in the leapsecond

           1995 December 31  23:59:60.5  (UTC)
           1996 January   1, 05:29:60.5  (UTC+5:30 --- Calcutta Time)
           1995 December 31, 20:29:60.5  (UTC-3:30 --- Newfoundland)
           1995 December 31  18:59:60.5  (EST)
           1995 December 31  17:59:60.5  (CST)
           1995 December 31  16:59:60.5  (MST)
           1995 December 31  15:59:60.5  (PST)


      In addition to specifying time zones, you may specify that the
      string be interpreted as a formal calendar representation in either
      the Barycentric Dynamical Time system (TDB) or the Terrestrial
      Dynamical Time system (TT).  In These systems there are no
      leapseconds.  Times in TDB are written as

        1988 June 13, 12:29:48 TDB

      TT times are written as:

        1988 June 13, 12:29:48 TT

      Finally, you may explicitly state that the time system is UTC

        1988 June 13, 12:29:48 UTC.


      Abbreviating Years
      ------------------

      Although it can lead to confusion, many people are in the
      habit of abbreviating years when they write them in dates.
      For example

         99 Jan 13,  12:28:24

      Upon seeing such a string, most of us would regard this
      as being 1999 January 13, 12:28:24 and not January 13 of
      the year 99.  This constructor interprets years that are less
      than 100 as belonging either to the 1900's or 2000's.  Years
      greater than 49 ( 50 - 99 ) are regarded as being an
      abbreviation with the '19' suppressed (1950 - 1999).  Years
      smaller than 50 ( 00 - 49 ) are regarded as being an
      abbreviation with the '20' suppressed (2000 - 2049).

      Note that in general it is usually a good idea to write
      out the year.  Or if you'd like to save some typing
      abbreviate 1999 as '99.

      If you need to specify an epoch whose year
      is less than 1000, we recommend that you specify the era
      along with the year.  For example if you want to specify
      the year 13 A.D. write it as

        13 A.D. Jan 12

      When specifying the era it should immediately follow the year.
      Both the A.D. and B.C. eras are supported.


      Changing Default Behavior
      -------------------------

      As discussed above, if a string is unlabeled, it is regarded
      as representing a string in the UTC time system on the
      Gregorian calendar.  In addition abbreviated years are
      regarded as abbreviations of the years from 1950 to 2049.

      You may modify these defaults through the methods timdef_
      and tsetyr.

      You may:

        Set the calendar to be Gregorian, Julian or a mixture of
        two via the timdef;

        Set the time system to be UTC, TDB, TT or any time zone
        via the method timdef;

        Set the range of year abbreviations to be any 100 year
        interval via the method tsetyr.

     See the methods texpyr_ and timdef for details on changing
     defaults.

     These alterations affect only the interpretation of unlabeled
     strings.  If an input string is labeled the specification
     in the label is used.

     If any component of a date or time is out of range, str2et
     regards the string as erroneous.  Below is a list of
     erroneous strings and why they are regarded as such.

        1997 Jan 32 12:29:29     --- there are only 31 days in January


        '98 Jan 12 13:29:29 A.M. --- Hours must be between 1 and 12
                                     inclusive when A.M. or P.M. is
                                     specified.

        1997 Feb 29, 12:29:20.0  --- February has only 29 days in
                                     1997. This would be ok if the
                                     year was 1996.


        1992 Mar 12 12:62:20     --- Minutes must be between 0 and 59
                                     inclusive.

        1993 Mar 18 15:29:60.5   --- Seconds is out of range for this
                                     date.  It would not be out of
                                     range for Dec 31 23:59:60.5 or
                                     Jun 30 23:59:60.5 because these
                                     can be leapseconds (UTC).

      Specifics On Interpretation of the Input String
      -----------------------------------------------

      The process of examining the string to determine its meaning is
      called "parsing" the string. The string is parsed by first
      determining its recognizable substrings (integers, punctuation
      marks, names of months, names of weekdays, time systems, time zones,
      etc.)  These recognizable substrings are called the tokens of the
      input string.  The meaning of some tokens are immediately
      determined. For example named months, weekdays, time systems have
      clear meanings.  However, the meanings of numeric components must be
      deciphered from their magnitudes and location in the string relative
      to the immediately recognized components of the input string.

      To determine the meaning of the numeric tokens in the input string,
      a set of "production rules" and transformations are applied to the
      full set of tokens in the string.  These transformations are
      repeated until the meaning of every token has been determined, or
      until further transformations yield no new clues into the meaning of
      the numeric tokens.

      1)  Unless the substring "JD" or "jd" is present, the string is
          assumed to be a calendar format (day-month-year or year and
          day of year).  If the substring JD or jd is present, the
          string is assumed to represent a Julian date.

      2)  If the Julian date specifier is not present, any integer
          greater than 999 is regarded as being a year specification.

      3)  A dash "-" can represent a minus sign only if it precedes
          the first digit in the string and the string contains
          the Julian date specifier (JD).  (No negative years,
          months, days, etc. are allowed).

      4)  Numeric components of a time string must be separated
          by a character that is not a digit or decimal point.
          Only one decimal component is allowed.  For example
          1994219.12819 is sometimes interpreted as the
          219th day of 1994 + 0.12819 days.  str2et does not
          support such strings.

          No exponential components are allowed.  For example you
          can't specify the Julian date of J2000 as 2.451545E6.

      5)  The single colon (:) when used to separate numeric
          components of a string is interpreted as separating
          Hours, Minutes, and Seconds of time.

      6)  If a double slash (//) or double colon (::) follows
          a pair of integers, those integers are assumed  to
          represent the year and day of year.

      7)  A quote followed by an integer less than 100 is regarded
          as an abbreviated year.  For example: '93 would be regarded
          as the 93rd year of the reference century.  See texpyr_
          for further discussion of abbreviated years.

      8)  An integer followed" by "B.C." or "A.D." is regarded as
          a year in the era associated with that abbreviation.

      9)  All dates are regarded as belonging to the extended
          Gregorian Calendar (the Gregorian calendar is the calendar
          currently used by western society).  See the method timedef_
          to modify this behavior.

      10) If the ISO date-time separator (T) is present in the string
          ISO allowed token patterns are examined for a match
          with the current token list.  If no match is found the
          search is abandoned and appropriate diagnostic messages
          are generated.

      11) If two delimiters are found in succession in the time
          string, the time string is diagnosed as an erroneous
          string.  (Delimiters are comma, white space, dash, slash,
          period, or day of year mark.  The day of year mark is a pair
          of forward slashes or a pair of colons.)

          Note the delimiters do not have to be the same. The pair
          of characters ",-" counts as two successive delimiters.

      12) White space and commas serve only to delimit tokens in the
          input string.  They do not affect the meaning of any
          of the tokens.

      13) If an integer is greater than 1000 (and the "JD" label
          is not present, the integer is regarded as a year.

      14) When the size of the integer components does not clearly
          specify a year the following patterns are assumed

          Calendar Format

              Year Month Day
              Month Day Year
              Year Day Month

              Where Month is the name of a month, not its numeric
              value.

              When integer components are separated by slashes (/)
              as in 3/4/5.  Month, Day, Year is assumed (2005 March 4)


           Day of Year Format

              If a day of year marker (// or ::) is present, the
              pattern I-I// or I-I:: (where I stands for an integer)
              is interpreted as Year Day-of-Year.  However, I-I/ is
              regarded as ambiguous.

   -Examples


      Below is a sampling of some of the time formats that are acceptable
      as inputs to str2et.  A complete discussion of permissible formats
      is given in the CSPICE method tpartv_ as well as the reference
      document time.req located in the "doc" directory of the Toolkit.

      ISO (T) Formats.

      String                        Year Mon  DOY DOM  HR Min Sec
      ----------------------------  ---- ---  --- ---  -- --- ------
      1996-12-18T12:28:28           1996 Dec   na  18  12  28 28
      1986-01-18T12                 1986 Jan   na  18  12  00 00
      1986-01-18T12:19              1986 Jan   na  18  12  19 00
      1986-01-18T12:19:52.18        1986 Jan   na  18  12  19 52.18
      1995-08T18:28:12              1995  na  008  na  18  28 12
      1995-18T                      1995  na  018  na  00  00 00


      Calendar Formats.

      String                        Year   Mon DOM  HR Min  Sec
      ----------------------------  ----   --- ---  -- ---  ------
      Tue Aug  6 11:10:57  1996     1996   Aug  06  11  10  57
      1 DEC 1997 12:28:29.192       1997   Dec  01  12  28  29.192
      2/3/1996 17:18:12.002         1996   Feb  03  17  18  12.002
      Mar 2 12:18:17.287 1993       1993   Mar  02  12  18  17.287
      1992 11:18:28  3 Jul          1992   Jul  03  11  18  28
      June 12, 1989 01:21           1989   Jun  12  01  21  00
      1978/3/12 23:28:59.29         1978   Mar  12  23  28  59.29
      17JUN1982 18:28:28            1982   Jun  17  18  28  28
      13:28:28.128 1992 27 Jun      1992   Jun  27  13  28  28.128
      1972 27 jun 12:29             1972   Jun  27  12  29  00
      '93 Jan 23 12:29:47.289       1993*  Jan  23  12  29  47.289
      27 Jan 3, 19:12:28.182        2027*  Jan  03  19  12  28.182
      23 A.D. APR 4, 18:28:29.29    0023** Apr  04  18  28  29.29
      18 B.C. Jun 3, 12:29:28.291   -017** Jun  03  12  29  28.291
      29 Jun  30 12:29:29.298       2029+  Jun  30  12  29  29.298
      29 Jun '30 12:29:29.298       2030*  Jun  29  12  29  29.298

      Day of Year Formats

      String                        Year  DOY HR Min Sec
      ----------------------------  ----  --- -- --- ------
      1997-162::12:18:28.827        1997  162 12  18 28.827
      162-1996/12:28:28.287         1996  162 12  28 28.287
      1993-321/12:28:28.287         1993  231 12  28 28.287
      1992 183// 12 18 19           1992  183 12  18 19
      17:28:01.287 1992-272//       1992  272 17  28 01.287
      17:28:01.282 272-1994//       1994  272 17  28 01.282
      '92-271/ 12:28:30.291         1992* 271 12  28 30.291
      92-182/ 18:28:28.281          1992* 182 18  28 28.281
      182-92/ 12:29:29.192          0182+ 092 12  29 29.192
      182-'92/ 12:28:29.182         1992  182 12  28 29.182


      Julian Date Strings

      jd 28272.291                  Julian Date   28272.291
      2451515.2981 (JD)             Julian Date 2451515.2981
      2451515.2981 JD               Julian Date 2451515.2981

                                   Abbreviations Used in Tables

                                      na    --- Not Applicable
                                      Mon   --- Month
                                      DOY   --- Day of Year
                                      DOM   --- Day of Month
                                      Wkday --- Weekday
                                      Hr    --- Hour
                                      Min   --- Minutes
                                      Sec   --- Seconds

 The default interpretation of a year that has been abbreviated
      with a leading quote as in 'xy (such as '92) is to treat the year as
      19xy if xy > 68 and to treat it is 20xy otherwise. Thus '69 is
      interpreted as 1969 and '68 is treated as 2068. However, you may
      change the "split point" and centuries through use of the CSPICE
      method tsetyr. See that method for a discussion of how you may
      reset the split point.

 All epochs are regarded as belonging to the Gregorian calendar.
      We formally extend the Gregorian calendar backward and forward in
      time for all epochs.

      +  When a day of year format or calendar format string is input and
      neither of the integer components of the date is greater than 1000,
      the first integer is regarded as being the year.


   -Restrictions

      None.

   -Literature_References

      None.

   -Author_and_Institution

      C.H. Acton         (JPL)
      N.J. Bachman       (JPL)
      W.L. Taber         (JPL)

   -Version

   -Index_Entries

       Convert a string to TDB seconds past the J2000 epoch



   

Throws:
SpiceErrorException
Method Detail

sub

public TDBDuration sub(Time t)
                throws SpiceException
Subtract a Time instance from this TDBTime, producing a TDBDuration.

Specified by:
sub in class Time
Throws:
SpiceException

add

public TDBTime add(Duration d)
            throws SpiceException
Add a Duration to a TDBTime.

Specified by:
add in class Time
Throws:
SpiceException

sub

public TDBTime sub(Duration d)
            throws SpiceException
Subtract a Duration from a TDBTime.

Specified by:
sub in class Time
Throws:
SpiceException

equals

public boolean equals(java.lang.Object obj)
Test two TDBTimes for equality.

Overrides:
equals in class java.lang.Object

hashCode

public int hashCode()
Return hash code for a TDBTime object. This method is overridden to support the overridden equals( Object ) method.

Overrides:
hashCode in class java.lang.Object

toString

public java.lang.String toString(java.lang.String picture)
                          throws SpiceErrorException
Convert a TDBTime to a formatted time string using a format picture. The format picture may be any supported by the SPICE routine TIMOUT.

Throws:
SpiceErrorException

toUTCString

public java.lang.String toUTCString(java.lang.String format,
                                    int precision)
                             throws SpiceErrorException
Convert a TDBTime to a formatted time string using a format code and an integer precision level for fractional seconds.

Throws:
SpiceErrorException

toString

public java.lang.String toString()
Convert a TDBTime to a formatted time string using a default picture. Note: this method overrides Object's "toString" method, and as such cannot throw a SpiceErrorException. Instead, if a conversion error occurs, the associated message is returned.

Overrides:
toString in class java.lang.Object

getTDBSeconds

public double getTDBSeconds()
                     throws SpiceErrorException
Express a TDBTime as a count of TDB seconds past J2000 TDB.

Specified by:
getTDBSeconds in class Time
Throws:
SpiceErrorException

JNISpice
version 2.0.0

JNISpice Alpha Test Version 2.0.0 28-JAN-2017 (NJB)