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.TH CONVCAL 1 "August 11, 2001" grace "User's Manual"
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convcal \- convert dates to different formats
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[\fIOPTIONS\fR] [\fIDATE\fR]
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\fBconvcal\fR is part of the \fIgrace\fR software package, an application for
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two-dimensional data visualization. \fBconvcal\fR converts dates from and to
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various formats. The following date formats are supported (hour, minutes and
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seconds are always optional):
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1999-12-31T23:59:59.999
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31/12/1999 23:59:59.999 or 31/12/99 23:59:59.999
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12/31/1999 23:59:59.999 or 12/31/99 23:59:59.999
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The formats are tried in the following order : users's choice,
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iso, european and us (there is no ambiguity between calendar
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formats and numerical formats and therefore no order is specified
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\fBconvcal\fR reads the dates either on the command line or in the
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standard input if the command line contains no date.
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The user's choice for the input format put one format before the other
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ones in the trial list, this is mainly useful for US citizen which
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would certainly prefer to have US format checked before european
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format. The default user's choice (nohint) does nothing so the
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following formats of the list are checked.
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The separators between various fields can be any characters in the set:
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" :/.-T". One or more spaces act as one separator, other characters
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can not be repeated, the T separator is allowed only between date and
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time, mainly for iso8601. So the string "1999-12 31:23-59" is allowed
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(but not recommended). The '-' character is used both as a
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separator (it is traditionally used in iso8601 format) and as the
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unary minus (for dates in the far past or for numerical
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dates). When the year is between 0 and 99 and is written with two
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or less digits, it is mapped to the era beginning at wrap year and
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ending at wrap year + 99 as follows :
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[wy ; 99] -> [ wrap_year ; 100*(1 + wrap_year/100) - 1 ]
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[00 ; wy-1] -> [ 100*(1 + wrap_year/100) ; wrap_year + 99]
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so for example if the wrap year is set to 1950 (which is the default
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value), then the mapping is :
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range [00 ; 49] is mapped to [2000 ; 2049]
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range [50 ; 99] is mapped to [1950 ; 1999]
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this is reasonably Y2K compliant and is consistent with current use.
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Specifying year 1 is still possible using more than two digits as
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follows : "0001-03-04" is unambiguously March the 4th, year 1, even
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if the user's choice is us format. However using two digits only is
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not recommended (we introduce a 2050 bug here so this feature
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should be removed at some point in the future ;-)
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Numerical dates (days and seconds formats) can be specified using
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integer, real or exponential formats (the 'd' and 'D' exponant
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markers from fortran are supported in addition to 'e' and 'E').
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They are computed according to a customizable reference date.
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The default value is given by the REFDATE constant in the source file.
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You can change this value as you want before compiling, and you can
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change it at will using the -r command line option. The default
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value in the distributed file is "-4713-01-01T12:00:00", it is a
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classical reference for astronomical events (note that the '-' is
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used here both as a unary minus and as a separator).
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The program can be used either for Denys's and gregorian
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calendars. It does not take into account leap seconds : you can
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think it works only in International Atomic Time (TAI) and not in
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Coordinated Unified Time (UTC) ... Inexistant dates are detected,
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they include year 0, dates between 1582-10-05 and 1582-10-14,
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February 29th of non leap years, months below 1 or above 12, ...
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A summary of the options supported by \fBconvcal\fR is included below.
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prints the help message on stderr and exits successfully
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\fB\-i\fR \fIformat\fR
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set user's choice for input format, supported formats are iso, european, us,
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days, seconds and nohint. At the beginning the input format is nohint, which
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means the program try to guess the format by itself, if the user's choice does
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not allow to parse the date, other formats are tried
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\fB\-o\fR \fIformat\fR
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force output format, supported formats are iso, european, us, days, seconds
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and nohint. At the beginning, the output format is nohint, which means the
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program uses days format for dates read in any calendar format and uses
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iso8601 for dates read in numerical format
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set reference date (the date is read using the current input format) at the
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beginning the reference is set according to the REFDATE constant in the code,
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which is -4713-01-01T12:00:00 in the distributed file.
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set the wrap year to year
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.I http://plasma-gate.weizmann.ac.il/Grace/
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This man-page was written by Jan Schaumann <jschauma@netmeister.org> as part of "The Missing
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Man Pages Project". Please see \fIhttp://www.netmeister.org/misc/m2p2/index.html\fR
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doc/convcal.1
