Working with dates that are seconds apart - datenum returns the exact same value. What am I doing wrong?

I'm trying to plot events on a time axis. The events are milliseconds apart. If I convert the timestamp of two events to a datenum I get the exact same result for different timestamps. See the following output:

datenum(20开发者_JS百科11,06,13,15,11,05.500)

ans =

7.3467e+005

datenum(2011,06,13,15,11,06.500)

ans =

7.3467e+005

The time between those two dates is one second apart. What am I doing wrong? Is there a way I can work with times like this?

Thanks -Daniel

Daniel, just store the data in variable, there is a a difference that's too small given your precision:

a = datenum(2011,06,13,15,11,05.500)
b = datenum(2011,06,13,15,11,06.500)
b - a
datevec(b-a)

a =

   7.3467e+05


b =

   7.3467e+05


ans =

   1.1574e-05


ans =

     0     0     0     0     0     1