Convert two different sets of dates and times to one shared vector

[ccbacca]

Say I have two different sets of dates and times. Is there a way to convert these to one same time vector with both initial date and time start at t = 0?:

01/05/10 15:00 EST <---- t=0
01/05/10 15:15 EST
01/05/10 15:30 EST
01/05/10 15:45 EST
01/05/10 16:00 EST
01/05/10 17:00 EST

and

05/28/10 13:00 EDT <---- t=0
05/28/10 13:15 EDT
05/28/10 13:30 EDT
05/28/10 13:45 EDT
05/28/10 14:00 EDT
05/28/10 14:30 EDT
05/28/10 15:00 EDT

[canoeron]

It looks like each value is increasing in increments of 15 minutes. Hence, the increment is described by 15/(60*24) = 15/1440
Try this: If you already have t0, then, t1 = t0 + (15/1440); t2= t1 + (15/1440); etc.