timout_c

Index Page timout_c
A B C D E F G H I J K L M N O P Q R S T U V W X
Procedure Abstract Required_Reading Keywords Brief_I/O Detailed_Input | Detailed_Output Parameters Exceptions Files Particulars Examples | Restrictions Literature_References Author_and_Institution Version Index_Entries
#### Procedure
       void timout_c ( SpiceDouble       et,
                       ConstSpiceChar  * pictur,
                       SpiceInt          lenout,
                       SpiceChar       * output )
#### Abstract
       This routine converts an input epoch represented in TDB seconds
       past the TDB epoch of J2000 to a character string formatted to
       the specifications of a user's format picture.
#### Required_Reading
       TIME
#### Keywords
       TIME
#### Brief_I/O
       Variable  I/O  Description
       --------  ---  --------------------------------------------------
       et         I   An epoch in seconds past the ephemeris epoch J2000.
       pictur     I   A format specification for the output string.
       lenout     I   The length of the output string plus 1.
       output     O   A string representation of the input epoch.
#### Detailed_Input
       et         a double precision representation of time in seconds
                  past the ephemeris epoch J2000.

       pictur     is a string that specifies how the output should be
                  presented.  The string is made up of various markers
                  that stand for various components associated with
                  a time.

                  There are five types of markers that may appear in a
                  format picture.  These are String Markers, Numeric
                  Markers, Meta markers, Modifier Markers and Literal
                  Markers.

                  The pictur string is examined and the various markers
                  are identified. The output time string is constructed
                  by replacing each of the identified markers with
                  an appropriate time component.

                  The various markers and their meanings are discussed
                  in the Particulars section below.

       lenout     The allowed length of the output string.  This length
                  must large enough to hold the output string plus the
                  terminator.  If the output string is expected to have x
                  characters, lenout needs to be x + 1.
#### Detailed_Output
       output     is the input epoch converted to the string format
                  described by pictur
#### Parameters
       None.
#### Exceptions
       1) The error SPICE(EMPTYSTRING) is signaled if the input
          string does not contain at least one character, since the
          input string cannot be converted to a Fortran-style string
          in this case.

       2) The error SPICE(NULLPOINTER) is signaled if either of
          the input or output string pointers is null.

       3) The user must pass a value indicating the length of the output
          string.  If this value is not at least 2, the error
          SPICE(STRINGTOOSHORT) is signaled.

       The user's processing environment must be properly initialized by
       loading a leapseconds kernel via the routine furnsh_c before calling
       this routine.  If a leapsecond kernel has not been loaded, an error
       will be signaled by routines called by timout_c.
#### Files
       A leapseconds kernel must be "loaded" via the routine furnsh_c
       prior to calling timout_c.
#### Particulars
       A format picture is simply a string of letters that lets
       timout_c know where various components of a time representation
       should be placed during creation of the time string.
       Here's an example of such a picture:

          MON DD,YYYY  HR:MN:SC.#### (TDB) ::TDB

       Here is a sample of the times that would be created by
       using this format.

          JAN 12,1992  12:28:18.2772 (TDB)
          FEB 13,1994  23:18:25.2882 (TDB)
          AUG 21,1995  00:02:00.1881 (TDB)

       As you can see from the samples above, the format picture
       specifies that every time string created should begin
       with a three-letter abbreviation for the month, followed
       by a space and the day of the month. The day of month is
       followed immediately by a comma and the year. The year
       component is followed by two spaces. Next are the output hours,
       represented as a two digit integer, a colon, minutes as
       a two digit integer, another colon, and seconds rounded
       to 4 decimal places and having a two digit integer part.
       This is followed by a space and the string "(TDB)". The
       special marker "::TDB" in the time picture is an
       ``invisible'' marker. It is used to specify the time
       system that should be used in creating the time string
       (in this case Barycentric Dynamical Time).

       timout_c does not recognize all of the parts
       of the time format picture in the example above. The list
       of recognized parts and unrecognized parts are listed in
       the table below.

         Recognized       Unrecognized
         ----------       ------------
         "MON"            " "
         "DD"             ","
         "YYYY"           "  "
         "HR"             ":"
         "MN"             "(TDB)"
         "SC"
         ".####"
         "::TDB"

       The unrecognized parts are called literal markers.  They are
       copied exactly as they appear in pictur into the output string.
       The recognized parts of the picture are replaced by a
       component of time or, as in the case of `::TDB' are used
       as instructions about the overall properties of the time
       string.

       The full list of recognized markers, their classification
       and meaning are given below.

       MARKER       CLASS     MEANING
       -----------  --------  -----------------------------------------
       ".##..."     modifier  represent a numeric component that
                              immediately precedes this in a decimal
                              format.  Number of decimal places
                              equals the number of "#" characters
       "::GCAL"     meta      dates are reported in Gregorian Calendar
       "::JCAL"     meta      dates are reported in Julian Calendar
       "::MCAL"     meta      dates after 15 October, 1582 are reported
                              in Gregorian Calendar, before that
                              dates are reported in Julian Calendar

       "::RND"      meta      round output to places specified by
                              least significant component

       "::TDB"      meta      all components should be TDB

       "::TDT"      meta      all components should be TDT

       "::TRNC"     meta      truncate all output components (default)
       "::UTC"      meta      all components should be UTC (default)
       "::UTC+h:m"  meta      all components in UTC offset by +h (hours)
                              and +m (minutes) so as to allow time zones.
       "::UTC-h:m"  meta      all components in UTC offset by -h (hours)
                              and -m (minutes) so as to allow time zones.
       "AMPM"       string    String (either "A.M."  or "P.M.")
                              indicating whether hours are before
                              or after noon.
       "ampm"       string    String (either "a.m."  or "p.m.")
                              indicating whether hours are before
                              or after noon.
       "AP"         numeric   AM/PM equivalents of the hour component
                              of a time.
       "DD"         numeric   Day of month
       "DOY"        numeric   Day of year
       "ERA"        string    String (either "B.C."  or "A.D.") giving
                              era associated with an epoch.
       "era"        string    String (either "b.c."  or "a.d.") giving
                              era associated with an epoch.
       "HR"         numeric   hour component of time
       "JULIAND"    numeric   julian date component of time
       "MM"         numeric   numeric representation of month component
       "MN"         numeric   minute component of time
       "MON"        string    upper case three letter abbreviation for
                              month
       "Mon"        string    capitalized three letter abbreviation for
                              month
       "mon"        string    lower case three letter abbreviation for
                              month
       "MONTH"      string    upper case full name of month
       "Month"      string    capitalized full name of month
       "month"      string    lower case full name of month
       "SC"         numeric   seconds component of time
       "SP1950"     numeric   seconds past 1950 component of time
       "SP2000"     numeric   seconds past 2000 component of time
       "YR"         numeric   last two digits of year component of time
       "YYYY"       numeric   year component of time
       "WEEKDAY"    string    upper case day of week
       "Weekday"    string    capitalized day of week
       "weekday"    string    lower case day of week
       "WKD"        string    upper case three letter abbreviation for
                              day of week.
       "Wkd"        string    capitalized three letter abbreviation for
                              day of week.
       "wkd"        string    lower case three letter abbreviation for
                              day of week.

       String Markers

          String markers are portions of the format picture that
          will be replaced with a character string representing the
          corresponding component of a time.

       Numeric Markers

          Numeric markers are portions of the format picture that
          will be replaced with a decimal string that represents
          the corresponding component of a time.

       Meta Markers

          Meta markers (listed under the class ``meta'' in the
          table above) are used to indicate `global' properties of
          your time string. You may specify time scale and how
          rounding should be performed on the components of time
          in your output string. Meta markers may be placed anywhere
          in your format picture. They do not contribute to placement
          of characters in output time strings. Also there are no
          restrictions on how many meta markers you may place in
          the format picture. However, if you supply conflicting
          `meta' markers (for example ::TDT and ::TDB) in your
          picture the first marker listed (in left to right order)
          overrules the conflicting marker that appears later in
          the picture.

       Modifier Markers

          The numeric markers listed in the table above stand
          for integers unless they are modified through use of a
          modifier marker. The strings

             .#
             .##
             .###
             .####

          are used to this end. When a numeric marker is followed
          immediately by one of these modifiers, the corresponding
          time component will be written with the number of decimal
          places indicated by number of successive occurrences of
          the character "#". Any numeric token may be modified.

       Rounding vs. Truncation

          The meta markers ::TRNC and ::RND allow you to control
          how the output time picture is rounded. If you specify
          ::TRNC all components of time are simply truncated to
          the precision specified by the marker and any modifier.
          If you specify ::RND the output time is rounded to the
          least significant component of the format picture. The
          default action is truncation.

          Whether an output time string should be rounded or
          truncated depends upon what you plan to do with the
          string. For example suppose you simply want to get the
          calendar date associated with a time and not the time of
          day. Then you probably do not want round your output.
          Rounding 1992 Dec 31, 13:12:00 to the nearest day
          produces 1993 Jan 1. Thus in this case rounding is probably
          not appropriate.

          However, if you are producing output for plotting using
          Julian Date, seconds past an 1950 or or seconds past
          2000, you will probably want your output rounded so as
          to produce a smoother plot.

       Time Zones

          The meta markers ::UTC+h:m  and ::UTC-h:m  allow you
          offset UTC times so that you may represent times in
          a time zone other than GMT.  For example you can
          output times in Pacific Standard time by placing the
          meta-marker ::UTC-8 in your format picture.

          For example if you use the picture

             YYYY Mon DD, HR:MN:SC ::UTC

          You will get output strings such as:

             1995 Jan 03, 12:00:00

          If you use the picture

             YYYY Mon DD, HR:MN:SC ::UTC-8

          You will get output strings such as:

             1995 Jan 03, 04:00:00

          Finally, if you use the picture

             YYYY Mon DD, HR:MN:SC ::UTC-8:15

          You will get output string

             1995 Jan 03, 03:45:00

          Note that the minutes are always added or subtracted
          based on the sign present in the time zone specifier.
          In the case of ::UTC+h:m, minutes are added. In the
          case ::UTC-h:m, minutes are subtracted.

          The unsigned part of the hours component can be no more
          than 12.  The unsigned part of the minutes can be no more
          than 59.

       Calendars

          The calendar currently used by western countries is the
          Gregorian Calendar.  This calendar begins on Oct 15, 1582.
          Prior to Gregorian Calendar the Julian calendar was used
          The last Julian calendar date prior to the beginning
          of the Gregorian Calendar is Oct 5, 1582.

          The primary difference between the Julian and Gregorian
          calendars is in the determination of leap years.
          Nevertheless both can be formally extended backward and
          forward in time indefinitely.

          By default timout_c uses the Gregorian Calendar (::GCAL) in the
          determination of the output string.  However, you may
          specify that timout_c use the Julian Calendar (::JCAL) or a
          mixture of both (::MCAL).  If you specify ::MCAL, epochs
          that occur after the beginning of the Gregorian Calendar
          will be represented using the Gregorian Calendar, epochs
          prior to the beginning of the Gregorian calendar will
          be represented using the Julian Calendar.

       Getting Software to Construct Pictures for You

          Although it is not difficult to construct time format
          pictures, you do need to be aware of the various markers
          that may appear in a format picture.

          There is an alternative means for getting a format picture.
          The routine tpictr_c constructs format pictures from a sample
          time string.  For example suppose you would like your
          time strings to look like the basic pattern of the string
          below.

             "Fri Jul 26 12:22:09 PDT 1996"

          You can call tpictr_c with this string, and it will create
          the appropriate pictur for use with timout_c.

             tpictr_c ( "Fri Jul 26 12:22:09 PDT 1996", pictur, OK )

          The result will be:

             "Wkd Mon DD HR:MN:SC (PDT) ::UTC-7"

          Note: not every date that you can read is interpretable
          by tpictr_c.  For example, you might be able to understand
          that 19960212121116 is Feb 12 1996, 12:11:16.  However,
          tpictr_c cannot recognize this string.  Thus it is important
          to check the logical OK to make sure that tpictr_c was able
          to understand the time picture you provided.

          Even thought tpictr_c can not recognize every time pattern
          that has been used by various people, it does recognize
          nearly all patterns that you use when you want to communicate
          outside your particular circle of colleagues.
#### Examples
       Suppose you need to create time strings similar to the
       default time string produced by the UNIX utility "date"
       (for example a string of the form "Thu Aug 01 09:47:16 PDT 1996")

       Make the following string assignment:

         pictur = "Wkd Mon DD HH:MN:SC PDT YYYY ::UTC-7";

       (Note the meta marker ::UTC-7 is used to adjust the output
       time system from UTC to PDT.  Also note that the substring PDT
       is a literal marker.  Without it, the time system would not
       appear in the output time string.

       Now for each time et for which an output time string is required
       make the call to timout_c below, and write the time string.

          timout_c ( et, pictur, lenout, string );
          printf ( "%s\n", string);

       Alternatively, you can let the routine tpictr_c create the timout_c
       time picture for you.

         tpictr_c ( "Thu Aug 01 09:47:16 PDT 1996", pictur, OK );

         if ( OK )
            {
            timout_c ( et, pictur, lenout, string );
            printf ( "%s\n", string);
            }
#### Restrictions
       None.
#### Literature_References
       None.
#### Author_and_Institution
       W.L. Taber     (JPL)
#### Version
       -CSPICE Version 1.1.1, 14-AUG-2006   (EDW)

          Edited incorrect description of output. Replace mention of
          ldpool_c with furnsh_c.

       -CSPICE Version 1.1.0, 09-FEB-1998 (NJB)

          Re-implemented routine without dynamically allocated, temporary
          strings.  Updated the Exceptions header section.

       -CSPICE Version 1.0.0, 25-OCT-1997   (EDW)
#### Index_Entries
       Convert and format d.p. seconds past J2000 as a string
#### Link to routine timout_c source file timout_c.c

    Thu Apr 16 08:59:22 2009