st: Errors, lack if precision in carrying out operations for some observations

["Jan Keil" <keilj051@newschool.edu>]

Dear Statalist,

I have the following problem:

Stata/SE 10.1 (Mac) does not undertake a simple operation on all of the 500,000 observations in my file (or does it with errors or not in a precise way).

I have 2 numeric variables, "gvkey" and "sid" (among others in the file) that are used to create a third, "id".

The commands are:

gen id = .
format id sid gvkey %16.2f
replace id = gvkey*1000 + sid


The result is that for some observations/rows the "id" variable is not calculated in a correct way.
Two examples are:

          id     gvkey    sid
 31567000.00  31567.00   1.00
119653096.00 119653.00  99.00

The values for "id" should be instead:

          id     gvkey   sid
 31567001.00  31567.00  1.00
119653099.00 119653.00 99.00


I tried different formats of the variables, I modified my command (calculated "id" with 2 steps), tried Stata 9, 10 and 11 (Mac and Windows).
I calculated a different "id" (my goal is to create a unique identifier) where I said "gen id = gvkey + sid/100" and Stata did not do it correctly to all observations. 
I also did that transformation in Excel and imported the resulting data as a csv file. "id" is calculated correctly in Excel, but when I import it to Stata it is not

Why is this happening?
What is the solution?

Thanks a lot in advance!
Jan


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