Error compounds adding date numbers

Hi, I am adding two date numbers. Upon multiple iterations the error in the addition seems to compound. For example if I add 10 seconds in date number the result seems to drop a few milliseconds every few iterations. Does anybody know the reason for that or a fix? P.S. I am using datenum function to generate date numbers.

[Sean de Wolski]

Can you give us a small example of what you're doing?

Answer 1

[C.J. Harris]

If you are using MATLAB date numbers they are stored as double precision numbers. This means the resolution of the date numbers are:

eps(now) * 84600 = 1.00582838058472e-005 (s)

As you can see this is roughly 0.01 milliseconds. Therefore rounding errors and so forth are very likely to result in you dropping (or adding) milliseconds here and there over many iterations (containing mathematical manipulations).