Converting Time Intervals into seconds

Hi! I am having issues converting a time interval (difference between 2 timestamps) into seconds.

I set instrument at 5 second intervals, but the instrument randomly missed 10-30 seconds of data.

'13:59:30'
'13:59:35'
'13:59:40'
'13:59:45'
'13:59:50'
'13:59:55'
'14:00:30'
'14:00:35'
'14:00:40'
'14:00:45'
'14:00:50'

I'm now trying to integrate my data over the time of our test Conc (i) in M/L^3 * flow rate (L^3/s) * dt (S) to get M.

However, I can't get the difference (for example) of 14:00:00 and 14:00:05 to just be 5.

I have tried second, datenum, datevec, and other functions to no avail. I seem to only get answers as 00:00:05, which causes my final answer to be xx:xx:xx, or when I use datenum(dt), I get a really small number (E-5).

Any help would be much appreciated!

thank you!

Answer 1

[dpb]

I don't have recent release so can't use datetime class, but datenum returns time in days and fractions thereof. Simply convert to seconds by the number of seconds/day...

>> dn=datenum(ts,'HH:MM:SS');  % ts is your sample timestamps
>> dt=diff(dn)*86400
dt =
  5.0000
  5.0000
  5.0000
  5.0000
  5.0000
 35.0000
  5.0000
  5.0000
  5.0000
  5.0000
>>

Or, of you want the time vector, simply subract the initial value...

>> t=(dn-dn(1))*86400
t =
       0
  5.0000
 10.0000
 15.0000
 20.0000
 25.0000
 60.0000
 65.0000
 70.0000
 75.0000
 80.0000
>>

[helen malenda]

Both seemed to work; thank you!

[dpb]

Glad to help.

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