subtract x hours from date variable -

[nazlikaramollaoglu]

I am trying to construct a time variable x hours before or after a specific date
Even though I constructed the time variable in tc format I am having leap second adjustment

What I am trying to do is to have eventtime_1hour seconds part to be exactly 00..What I got is the following:

lets assume x is 1 hour

gen a=60*60000 (1 hour in miliseconds)

. gen eventtime_1hour= eventtime- a

. format %tc eventtime_1hour

is there anyway to have eventtime_1hour to be 26mar1989 02:00:00; 24sep1989 03:00:00 etc....

a eventtime_1hour eventtime
3600000 26mar1989 02:00:05 26mar1989 03:00:00
3600000 24sep1989 02:59:43 24sep1989 04:00:00
3600000 31dec1989 22:59:53 01jan1990 00:00:00
3600000 31dec1989 23:00:59 01jan1990 00:01:00
3600000 31dec1989 23:02:04 01jan1990 00:02:00
3600000 31dec1989 23:03:10 01jan1990 00:03:00
3600000 31dec1989 23:04:15 01jan1990 00:04:00

[Nick Cox]

Use round(<datetime>, 60*60000)

[Svend Juul]

The suggested round() does not solve the problem; it rounds the result to the nearest hour, and I don't think that is what n??? wants (we prefer seeing real names). It is a matter of precision; see help precision. Generate the eventtime variables as double:

gen double eventtime_1hour = eventtime-a

[Svend Juul]

I misread the question. I also think Nick did; n??? wanted rounding to the nearest minute, not the nearest hour. I stored the variables of interest as double:

gen double a = 60*60*1000
gen double eventtime_1hour = round(eventtime+a, 60000)
format eventtime* %tc

. list eventtime*, clean
                eventtime      eventtime_1hour 
  1.   26mar1989 02:00:05   26mar1989 03:00:00 
  2.   24sep1989 02:59:43   24sep1989 04:00:00 
  3.   31dec1989 22:59:53   01jan1990 00:00:00 
  4.   31dec1989 23:00:59   01jan1990 00:01:00 
  5.   31dec1989 23:02:04   01jan1990 00:02:00 
  6.   31dec1989 23:03:10   01jan1990 00:03:00 
  7.   31dec1989 23:04:15   01jan1990 00:04:00

[nazlikaramollaoglu]

Thanks so much!
Nazlı