Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: Comparison of time entries
Replies: 11   Last Post: Apr 25, 2012 1:33 PM

 Messages: [ Previous | Next ]
 Barry Williams Posts: 312 Registered: 6/14/06
Re: Comparison of time entries
Posted: Apr 25, 2012 9:55 AM

"Johannes " <j.luthe@gmx.de> wrote in message <jn8tto\$t29\$1@newscl01ah.mathworks.com>...
> But I saw, that I haven't made myself clear enough and I even discovered a bad mistake in my problem described above.
>
> My original problem is what follows:
>
> start = datenum('14:32:41','hh:mm:ss') = 7.358125838078704e+005
> end = datenum('15:00:49','hh:mm:ss') = 7.348386255671296e+005
>
> end - start = -9.739582407408161e+002
>
> So I get for the later time a value that's smaller than that for the earlier time. How is that possible?

Read doc datestr for permitted formats, then compare the results of using:
datenum('14:32:41','hh:mm:ss') and datenum('14:32:41','HH:MM:SS')

Your problem will also be apparent if you use datestr to reverse your original entries, e.g., datestr(7.358125838078704e+005) and datestr(7.348386255671296e+005).
You will notice that they fall in different years because of the difficulty that Matlab has interpreting your format.

As another matter, avoid using a keyword, like end, as a variable.

Barry

Date Subject Author
4/24/12 Johannes
4/24/12 dpb
4/24/12 Steven Lord
4/25/12 Johannes
4/25/12 dpb
4/25/12 dpb
4/25/12 dpb
4/25/12 Barry Williams
4/25/12 Johannes
4/25/12 dpb
4/25/12 Barry Williams
4/25/12 Steven Lord