CDF_EPOCH_UNIXTIME
==================

The CDF_EPOCH_UNIXTIME function converts time(s) in CDF_EPOCH, CDF_EPOCH16 or
CDF_TIME_TT2000 (TT2000) to/from Unix time(s). The source time(s) can be a
scalar or array.

The CDF_EPOCH time is milliseconds from 0000-01-01 00:00:00.000 in idl double.
The CDF_EPOCH16 (long epoch) time is picoseconds from 0000-01-01 00:00:00.000 in
idl double complex. The TT2000 time in nanoseconds from J2000 with leap seconds
in idl long64. The unix time is seconds from 1970-01-01 00:00:00 in idl double. 
The Unix time can have sub-second, with a time resolution of microseconds, in
its fractional part.

Note: Since TT2000 and CDF_EPOCH16 has higher time resolution, the converted
      time might not preserve the full resolution for sub-microseconds. 
      CDF_EPOCH does not have the time resolution for microseconds. The
      conversion will not preserve it if the Unix time has that.

Examples

To convert the CDF_EPOCH times at 1969-12-31T23:59:59.000,
1970-01-01T00:00:00.000 and 1970-01-01T00:00:01.000 to their corresponding unix
times.

V3 = CDF_PARSE_EPOCH (['1969-12-31T23:59:59.000','1970-01-01T00:00:00.000',$
                       '1970-01-01T00:00:01.000'])
help, V3
V3              DOUBLE    = Array[3]
unixtimes = CDF_EPOCH_UNIXTIME (V3)
print, unixtimes
      -1.0000000       0.0000000       1.0000000

To convert unix times back to CDF_EPOCH:

E3 = CDF_EPOCH_UNIXTIME (unixtimes, /EPOCH)
print, CDF_ENCODE_EPOCH(E3)
1969-12-31T23:59:59.000 1970-01-01T00:00:00.000 1970-01-01T00:00:01.000

To convert the same unix times to TT2000:

T3 = CDF_EPOCH_UNIXTIME (unixtimes, /TT2000)
help, T3
T3              LONG64    = Array[3]
print, CDF_ENCODE_TT2000(T3)
1969-12-31T23:59:59.000000000 1970-01-01T00:00:00.000000000 
1970-01-01T00:00:01.000000000

To convert the same unix times to CDF_EPOCH16:

TT2000 = CDF_EPOCH_UNIXTIME (unixtimes, /LONGEPOCH)
help, TT2000
TT2000             DCOMPLEX  = Array[3]
print, CDF_ENCODE_TT2000(TT2000)
1969-12-31T23:59:59.000000000000 1970-01-01T00:00:00.000000000000
1970-01-01T00:00:01.000000000000

Syntax

Result = CDF_EPOCH_UNIXTIME (Time [, /EPOCH] [, /LONGEPOCH] $
                                  [, /TT2000])

Arguments

Time

The time, unix time or CDF based time, to be converted. It can be a scalar value
or an array of values. Without any keyword, it is converting a CDF based time(s)
to unix time(s). 

Keywords

EPOCH

Set this keyword to convert a unix time(s) to a CDF_EPOCH data type time(s).

LONGEPOCH

Set this keyword to convert a unix time(s) to a CDF_EPOCH16 data type time(s).

TT2000

Set this keyword to convert a unix time(s) to a CDF's TT2000 data type time(s).

Version History

Pre 4.0

Introduced

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