cdflib.breakdownTT2000

Convert CDF_TIME_TT2000 timestamp to time components

Since R2022b

Syntax

timeVec = cdflib.breakdownTT2000(tt2000)

Description

timeVec = cdflib.breakdownTT2000(tt2000) decomposes a CDF_TIME_TT2000 timestamp into individual UTC-based time components.

• If tt2000 is an integer scalar, then timeVec is a column vector.

• If tt2000 is an n-element integer vector, then timeVec is a 9-by-n matrix.

Examples

Convert J2000 to Coordinated Universal Time

Use cdflib.breakdownTT2000 to form the vector myTime of individual time components for J2000 (January 1, 2000, 12:00:00 Terrestrial Time) by passing int64(0) as the input.

j2000 = int64(0);
myTime = cdflib.breakdownTT2000(j2000)

myTime = 9×1

        2000
           1
           1
          11
          58
          55
         816
           0
           0

Report myTime as a datetime value in Coordinated Universal Time (UTC).

myTimeCell = num2cell(myTime(1:7));
myTimeCell{7} = myTimeCell{7}+myTime(8)/1e3+myTime(9)/1e6;
j2000_utc = datetime(myTimeCell{:},"TimeZone","UTCLeapSeconds")

j2000_utc = datetime
   2000-01-01T11:58:55.816Z

Read Sample CDF_TIME_TT2000 Data

Open the example_364.cdf CDF file and prepare to read CDF_TIME_TT2000 data.

cdfid = cdflib.open("example_364.cdf");
varID = 7;                                          % Contains CDF_TIME_TT2000 data
numRecs = cdflib.getVarNumRecsWritten(cdfid,varID); % Read all records
tt2000Data = zeros(1,numRecs,"int64");              % Preallocate array

Read CDF_TIME_TT2000 data in native int64 form.

for i = 0:numRecs-1
    tt2000Data(i+1) = cdflib.getVarData(cdfid,varID,i);
end
tt2000Data' % Display as column vector for readability

ans = 8x1 int64 column vector

   536500865284200300
   536500866284200300
   536500867284200300
   536500868284200300
   536500869284200300
   536500870284200300
   536500871284200300
   536500872284200300

Decompose the eight dates into their individual time components.

dateMatrix = cdflib.breakdownTT2000(tt2000Data)

dateMatrix = 9×8

        2016        2016        2016        2016        2017        2017        2017        2017
          12          12          12          12           1           1           1           1
          31          31          31          31           1           1           1           1
          23          23          23          23           0           0           0           0
          59          59          59          59           0           0           0           0
          57          58          59          60           0           1           2           3
         100         100         100         100         100         100         100         100
         200         200         200         200         200         200         200         200
         300         300         300         300         300         300         300         300

Input Arguments

tt2000 — CDF_TIME_TT2000 timestamp

integer scalar | integer vector

CDF_TIME_TT2000 timestamp, specified as an integer scalar or integer vector. For more information about CDF_TIME_TT2000 timestamps, see the More About section.

Example: int64(1e18)

Example: int64([0 -1])

Data Types: int64

Output Arguments

timeVec — Individual time components

vector | matrix

Individual time components, returned as a 9-by-1 vector or a 9-by-n matrix, where n is the number of timestamps converted.

Each column of timeVec contains the individual time components of one of the entries in tt2000. Each row of timeVec is a time component, according to this list:

Row	Value	Range
1	Year (CE)	[1707, 2292]
2	Month	[1, 12]
3	Day	[1, 31]
4	Hour	[0, 23]
5	Minute	[0, 59]
6	Second	[0, 59] (or [0, 60] if leap second)
7	Millisecond	[0, 999]
8	Microsecond	[0, 999]
9	Nanosecond	[0, 999]

Data Types: double

More About

CDF_TIME_TT2000 Timestamp

A CDF_TIME_TT2000 timestamp represents the number of nanoseconds elapsed since J2000. J2000 represents January 1, 2000, 12:00:00 Terrestrial Time (TT). TT differs slightly from Coordinated Universal Time (UTC). A TT time can be derived from a UTC time by adding n + 32.184 s to the UTC time, where n is the number of leap seconds that were added between 1960 and the UTC time. For more information, see Requirements for handling leap seconds in CDF and Leap second table.

Tips

• This function corresponds to the CDF library C API routine breakdownTT2000.

• To use this function, you must be familiar with the CDF C interface. You can access the CDF documentation at the CDF website.

Version History

Introduced in R2022b