Inverse of posix time
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Hello,
O was wondering if there is a function in matlab that does the opposite as posix time. Indeed, I have a UNIX time (1443002431.224) and I want to convert it into a date with hour, minute and second.
How can I do it ? Does it exist a function to do this ?
Thank you very much for your help !!
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Accepted Answer
Guillaume
on 28 Sep 2015
d = datetime(1443002431.224, 'ConvertFrom', 'posixtime')
4 Comments
Haris K.
on 16 May 2020
@Peter Perkins if you format the output of the resulted datetime as 'dd-MMM-yyyy HH:mm:ss.SSS' both:
unix_t = 1443002431.224;
datetime(unix_t, 'ConvertFrom', 'posixtime')
datetime(round(1000*unix_t),'ConvertFrom','epochtime',"TicksPerSecond",1000)
return the same output, i.e. 23-Sep-2015 10:00:31.224. So what is the round-off introduced?
Peter Perkins
on 28 Jul 2020
Well, I misspoke, sort of.
The round-off is introduced in unix_t = 1443002431.224. That is not a value that is representable exactly in floating point. However, because of the extremely smart people who created IEEE754 etc. way back when, it turns out that 1443002431.224*1000 is exactly 1443002431224. And that multiplication happens inside datetime, without you needing to do it as in my code. That's what saves this.
I think that should be true for anything specified to milliseconds.
More Answers (2)
Emre Güngör
on 29 Nov 2018
You need 2018 version
1 Comment
Steven Lord
on 29 Nov 2018
Not true. datetime was introduced in release R2014b and the documentation for that function in that release lists the 'ConvertFrom', 'posixtime' syntax. When I run Guillaume's code in release R2014b I receive the same answer as if I created a datetime for January 1st, 1970 and added that many seconds to it. Both those answers matched the results I received for those same computations in release R2018b and the result I received using an online UNIX epoch converter.
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