CONVCAL(1)							   User's Manual							CONVCAL(1)

NAME

       convcal - convert dates to different formats

SYNOPSIS

       convcal [OPTIONS] [DATE]

DESCRIPTION

       convcal	is  part  of the grace software package, an application for two-dimensional data visualization. convcal converts dates from and to
       various formats. The following date formats are supported (hour, minutes and seconds are always optional):

       iso    1999-12-31T23:59:59.999

       european
	      31/12/1999 23:59:59.999 or 31/12/99 23:59:59.999

       us     12/31/1999 23:59:59.999 or 12/31/99 23:59:59.999

       days   123456.789

       seconds
	      123456.789

       The formats are tried in the following order : users's choice, iso, european and us (there is no ambiguity  between  calendar  formats  and
       numerical formats and therefore no order is specified for them).

USAGE

       convcal reads the dates either on the command line or in the standard input if the command line contains no date.

       The  user's  choice for the input format put one format before the other ones in the trial list, this is mainly useful for US citizen which
       would certainly prefer to have US format checked before european format. The default user's choice (nohint) does nothing so  the  following
       formats of the list are checked.

       The separators between various fields can be any characters in the set: " :/.-T". One or more spaces act as one separator, other characters
       can not be repeated, the T separator is allowed only between date and time, mainly for iso8601. So the string "1999-12 31:23-59" is allowed
       (but  not  recommended).  The '-' character is used both as a separator (it is traditionally used in iso8601 format) and as the unary minus
       (for dates in the far past or for numerical dates). When the year is between 0 and 99 and is written with two or less digits, it is  mapped
       to the era beginning at wrap year and ending at wrap year + 99 as follows :

       [wy ; 99] -> [ wrap_year ; 100*(1 + wrap_year/100) - 1 ]

       [00 ; wy-1] -> [ 100*(1 + wrap_year/100) ; wrap_year + 99]

       so for example if the wrap year is set to 1950 (which is the default value), then the mapping is :

       range [00 ; 49] is mapped to [2000 ; 2049]

       range [50 ; 99] is mapped to [1950 ; 1999]

       this  is  reasonably  Y2K  compliant and is consistent with current use.  Specifying year 1 is still possible using more than two digits as
       follows : "0001-03-04" is unambiguously March the 4th, year 1, even if the user's choice is us format. However using two digits only is not
       recommended (we introduce a 2050 bug here so this feature should be removed at some point in the future ;-)

       Numerical  dates  (days	and seconds formats) can be specified using integer, real or exponential formats (the 'd' and 'D' exponant markers
       from fortran are supported in addition to 'e' and 'E').	They are computed according to a customizable reference date.  The  default  value
       is given by the REFDATE constant in the source file.  You can change this value as you want before compiling, and you can change it at will
       using the -r command line option. The default value in the distributed file is "-4713-01-01T12:00:00", it  is  a  classical  reference  for
       astronomical events (note that the '-' is used here both as a unary minus and as a separator).

       The  program  can  be  used either for Denys's and gregorian calendars. It does not take into account leap seconds : you can think it works
       only in International Atomic Time (TAI) and not in Coordinated Unified Time (UTC) ...  Inexistant dates are detected, they include year	0,
       dates between 1582-10-05 and 1582-10-14, February 29th of non leap years, months below 1 or above 12, ...

OPTIONS

       A summary of the options supported by convcal is included below.

       -h     prints the help message on stderr and exits successfully

       -i format
	      set  user's  choice for input format, supported formats are iso, european, us, days, seconds and nohint.	At the beginning the input
	      format is nohint, which means the program try to guess the format by itself, if the user's choice does not allow to parse the  date,
	      other formats are tried

       -o format
	      force  output  format,  supported  formats  are iso, european, us, days, seconds and nohint.  At the beginning, the output format is
	      nohint, which means the program uses days format for dates read in any calendar format and uses iso8601 for dates read in  numerical
	      format

       -r date
	      set  reference date (the date is read using the current input format) at the beginning the reference is set according to the REFDATE
	      constant in the code, which is -4713-01-01T12:00:00 in the distributed file.

       -w year
	      set the wrap year to year

SEE ALSO

       grace(1)

       http://plasma-gate.weizmann.ac.il/Grace/

AUTHOR

       Luc Maisonobe

       This man-page was  written  by  Jan  Schaumann  <jschauma@netmeister.org>  as  part  of	"The  Missing  Man  Pages  Project".   Please  see
       http://www.netmeister.org/misc/m2p2/index.html for details.

grace								  August 11, 2001							CONVCAL(1)