how to convert 18 digits timestamp to readable date and time in MATLAB

I have data with a time step consists of 18 digits such as 634019142119225390. This date should be in February 2010 by the way.

How can i convert this into readable date and time in MATLAB ?

Unfortunately i don't know what is the format of this timestamp. Is it UNIX or Julian or what.

Many Thanks in advance

[the cyclist]

Number of seconds since the big bang?

[Brendan Hamm]

Maybe with more samples one could deduce what the measurement unit is and then the base time. With one sample the cyclists guess is as good as any. I might guess that the measurements are in mico or nano seconds though.

[Guillaume]

It's the time in 100-nanoseconds since Jan 1, 1 UTC.

[ameen]

Thank you all for your comments. More samples are provided.

634019142119225390

634019142129597610

634019142139821660

[Guillaume]

I'm not sure why you're providing more samples. As far as I can tell, I've answered your question.

[ameen]

I added more samples as required by @ Brendan Hamm

Answer 1

[Guillaume]

This page may be useful.

Most likely, your timestamp is a .Net System.DateTime

>>ts = int64(634019142119225390);
>>dt = System.DateTime(ts);   %Note that you need to be on Windows for this to work
>>dt.ToString
ans = 

16/02/2010 00:00:00

[ameen]

Thank you for your kind reply.

How can i do the same for multiple timestamps ?

I made a new variable in the workspace contains my timestamps then

>>ts = int64(variable);

>>dt = System.DateTime(ts);

But i receive an error ' Error using System.DateTime. No constructor 'System.DateTime' with matching signature found.'

[Guillaume]

The simplest way would be to use arrayfun (or a loop). You can't pass arrays to System.DateTime

tss = [int64(634019142119225390) int64(634019142129597610) int64(634019142139821660)]; %see note below
dts = arrayfun(@System.DateTime, tss, 'UniformOutput', false);
dtastring = cellfun(@(dt) char(dt.ToString), dts, 'UniformOutput', false)

Note: because you're dealing with 64-bit integers that cannot be represented exactly as double, you have to be extremely careful not to use double even temporarily. I strongly suspect that your line ts = int64(variable) does not work. In particular

v = [634019142119225390 634019142129597610 634019142139821660]; v is double
ts = int64(v)

does not work, because of the storage as double. And

ts = int64([634019142119225390 634019142129597610 634019142139821660])

does not work either because the array is constructed as double.

[ameen]

Thank you very much for your reply and help.

why these two timestamps give me the same date and time ?

634018095130693130 and 634018095139168740

[Guillaume]

As per the documentation of System.DateTime, its resolution is 100 nanoseconds. Therefore the difference between your two timestamps is only 1 microsecond.

You need to add 10,000,000 (1e7) to just go up one second.

[ameen]

Thank you very much Guillaume for your help.

Answer 2

[Peter Perkins]

Another option, if you have MATLAB R2014b or later, is this:

>> x = [uint64(634019142119225390) uint64(634019142129597610) uint64(634019142139821660)]
x =
 634019142119225390   634019142129597610   634019142139821660
>> datetime(double(x)/1e7,'ConvertFrom','epochtime','Epoch','1-Jan-0001','Format','dd-MMM-yyyy HH:mm:ss.SSSSSSSSS')
ans = 
   16-Feb-2010 10:50:11.922531250   16-Feb-2010 10:50:12.959757812   16-Feb-2010 10:50:13.982171875

But that's not exactly right -- those uint64's are larger than flintmax, so casting them to double introduces round-off. You may not care about 100ns resolution. If you only cared about 1ms resolution, you could do this:

>> datetime(double(x/1e4)/1e3,'ConvertFrom','epochtime','Epoch','1-Jan-0001','Format','dd-MMM-yyyy HH:mm:ss.SSS')
ans = 
   16-Feb-2010 10:50:11.923   16-Feb-2010 10:50:12.960   16-Feb-2010 10:50:13.982

But to get exactly what you started with, do this:

>> secs = (x-.5e7)/1e7
secs =
          63401914211          63401914212          63401914213
>> milliSecs = double(x - uint64(secs)*1e7)/1e4
milliSecs =
                   922.539                   959.761                   982.166
>> datetime(secs,'ConvertFrom','epochtime','Epoch','1-Jan-0001','Format','dd-MMM-yyyy HH:mm:ss.SSSSSSSSS') + milliseconds(milliSecs)
ans = 
   16-Feb-2010 10:50:11.922539000   16-Feb-2010 10:50:12.959761000   16-Feb-2010 10:50:13.982166000

[ameen]

Thank you for your kind reply and help.

Answer 3

[William Bertram]

634019142119225390 appears to be the number of nanoseconds that has elapsed since 01/01/0001 00:00. Here is a quick Powershell to convert that to human readable:

$timestamp = 636244407153688066 / 10000000

$epochDate = [datetime]"01/01/0001 00:00"

$epochDate.AddSeconds($timestamp)