Please advice how to convert date array to seconds format

here by attaching date formats and their respective code, kindly advice how can i convert it to seconds form as attached..

Data=readtable('axeaload.xlsx'); 
testdates = Data{1:end,1};
date_num = datenum(testdates);

[Walter Roberson]

Seconds since what time?

Or based upon what input?

datenum reflect full days. Seconds on the order of 120 reflect approximately every 2 minutes.

It seems more likely that you have a duration of some kind inside your xlsx file.

[NN]

thanks for your reply .I have attached the excel file .Please check

But i understand it is hourly basis in excel file

[Walter Roberson]

Might I suggest that what you want is minutes and not seconds?

Data = readtable('axeaload.xlsx');
dt = Data{:,1} + hours(Data{:,2});

minutes_inside_day = minutes(dt - dateshift(dt, 'start', 'day'));

minutes_since_start = minutes(dt - dateshift(dt(1), 'start', 'day'));

Depending what you are trying to do.

If you are wanting to do minutes inside the day, then a simpler way is just

minutes_inside_day = Data{:,2} * 60;

[NN]

Thank you it works, but why it shows from 120,then 180...

Its not showing 60 sec initially !

[Walter Roberson]

... It doesn't start with 120 ?

Data = readtable('axeaload.xlsx');
dt = Data{:,1} + hours(Data{:,2});
minutes_inside_day = minutes(dt - dateshift(dt, 'start', 'day'));
minutes_since_start = minutes(dt - dateshift(dt(1), 'start', 'day'));

minutes_inside_day(1:3)

ans = 3×1

60 120 180

minutes_since_start(1:3)

ans = 3×1

60 120 180

minutes_inside_day = Data{:,2} * 60;
minutes_inside_day(1:3)

ans = 3×1

60 120 180

Perhaps the 60 scrolled off your command window and you need to scroll back to see it?

[NN]

Thank you , i will do it again

[NN]

I starts with 120 only :-(

[Walter Roberson]

Try

Data = readtable('axeaload.xlsx', 'readvariablenames', false);

I speculate you might be using an older version that tended to be weaker in figuring out whether the first line was variable names or not.

[NN]

ok/ sure

[Walter Roberson]

Did that solve the problem?

[NN]

yes

[NN]

thank you very much

[NN]

I request you to look into the below query as well.

When i import time series data from matlab to simulink,it appears as individual data not as corresponding to time.(image attached).

i used the below format for below workspace

[time Youtput]

time and Youtput are 1*360 double format

[NN]

this has been posted here :

https://www.mathworks.com/matlabcentral/answers/720499-importing-data-rom-matlab-to-simulink