Converting UTC time into ordinal numbers


I am trying to analyze my data from ODK and stumped in converting UTC
time into ordinal numbers which reflects the actual time intervals.What I
would like to do is converting the given times such as

Wed Feb 19 16:02:51 UTC 2014

Wed Feb 19 19:29:45 UTC 2014

Thu Feb 20 20:01:07 UTC 2014

into time format which reflects the cumulated time interval from
the starting point as below.

16.01 (or 0)

19.50 (or 3.50)

44.00 (0r 24.50)

If anybody has experience in converting the time format, please help me

FYI, the time converting is needed for statistical analysis using SAS.