Calculate difference between two times?...something it's wrong here¡

Question

Rapala 2014-9-17

1
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回答： Star Strider 2014-9-17

I would be very grateful if someone could help me with the following problem, I try to subtract dates, but clearly the result is not what I expect....look¡

>>date =

        2012           9          25           0           0           0
        2012           9          23          21           0           0

>>d=datenum(date)

d =

0e+05 *
3514
3514

>>difference=d(1)-d(2);

ans =

1.1250

>>datestr(difference,'yyyy mm dd HH MM SS')

ans =

0000 01 01 03 00 00 % should be 0000 00 01 03 00 00

Thanks

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Answer 1

Star Strider 2014-9-17

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In the datevec documentation, this appears:

Limitations

When computing date vectors, MATLAB sets month values less than 1 to 1. Day values, D, less than 1 are set to the last day of the previous month minus D. However, if 0 ≤ DateNumber < 1, then datevec(DateNumber) returns a date vector of the form [0 0 0 H MN S], where H, MN, and S are hours, minutes, and seconds, respectively.

This does not appear in the datestr documentation, but I would be surprised if it does not apply there as well, since both datestr and datevec give the same results to your calculations.

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Answer 2

José-Luis 2014-9-17

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编辑：José-Luis 2014-9-17

在 MATLAB Online 中打开

What makes you think it should be 0000 00 01 03 00 00?

From the documentation:

A serial date number represents a calendar date as the number of days that has passed since a fixed base date. In MATLAB, serial date number 1 is January 1, 0000.

If you subtract two datenumbers, the result will not be the time elapsed between the two dates.

datevec(723300 - 723297)

If you want the elapsed time:

etime(datevec(723300),datevec(723297)) %in seconds