spreadsheet dates

[Allin Cottrell <cottrell wfu edu>]

I'm writing a convertor for numeric spreadsheet-type dates into 
calendar dates, and I've run into some confusion.  I've created
a little test sheet where the first column contains the numbers
0, 1, 33105.  I then copy these values into a second column and
apply YYYY-MM-DD date formatting.

If I do this in gnumeric 1.5.5, I get

     0  1899-12-31
     1  1900-01-01
 33105  1990-08-20

But in OpenOffice.org 1.1.4 I get

     0  1899-12-30
     1  1899-12-31
 33105  1990-08-20

My own convertor yields 1990-08-21 when fed the value 33105
with a base of 0 = 1899-12-31 (1 = 1900-01-01).

Can anyone help me understand what's going on here?  Thanks.

--
Allin Cottrell
Department of Economics
Wake Forest University, NC