posixtime

Convert MATLAB datetime to POSIX time

Syntax

p = posixtime(t)

Description

p = posixtime(t) returns POSIX^® times equivalent to the datetime values in t. The POSIX time is the number of seconds (including fractional seconds) elapsed since 00:00:00 1-Jan-1970 UTC (Coordinated Universal Time), ignoring leap seconds. p is a double array.

• If the time zone of t is not specified, then posixtime treats the times in t as UTC times. This interpretation might differ from your treatment of “unzoned” datetime arrays in other contexts. For example, you might think of datetime('now') as returning your local time. However, posixtime interprets it as a UTC time.

• If the time zone of t is specified, then posixtime uses the offset for the time zone to compute POSIX times with respect to UTC.

The best practice is to specify the time zone of t before calling posixtime.

Examples

Convert Datetime Array to POSIX Times

Create datetime values and convert them to the equivalent POSIX® times. Show the differences in POSIX times between zoned and unzoned datetime values. The best practice is to specify a time zone for a datetime array before calling posixtime.

Create a datetime array and specify its time zone.

t1 = datetime('2016-07-29 10:05:24') + calmonths(1:3);
t1.TimeZone = 'America/New_York'

t1 = 1x3 datetime
   29-Aug-2016 10:05:24   29-Sep-2016 10:05:24   29-Oct-2016 10:05:24

Convert t1 to the equivalent POSIX times. posixtime accounts for the time zone offset when it computes POSIX times.

format longG
p1 = posixtime(t1)

p1 = 1×3

                1472479524                1475157924                1477749924

Create a datetime array with the same values as t1, but with no time zone. Convert it to the equivalent POSIX times. posixtime treats the times in t2 as UTC times, with no time zone offset.

t2 = datetime('2016-07-29 10:05:24') + calmonths(1:3);
p2 = posixtime(t2)

p2 = 1×3

                1472465124                1475143524                1477735524

Show the differences between p2 and p1. The differences are equal to the time offset, in seconds, between UTC and the time zone of t1.

p2 - p1

ans = 1×3

      -14400      -14400      -14400

Input Arguments

t — Input date and time

datetime array

Input date and time, specified as a datetime array.

Extended Capabilities

Tall Arrays

Calculate with arrays that have more rows than fit in memory.

The posixtime function fully supports tall arrays. For more information, see Tall Arrays.

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Thread-Based Environment

Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

This function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.

Distributed Arrays

Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

This function fully supports distributed arrays. For more information, see Run MATLAB Functions with Distributed Arrays (Parallel Computing Toolbox).

Version History

Introduced in R2014b