errors on date

[David Gonzalez Marquez]

Hi!

I am student of computer science at university of Buenos Aires. I am
using the command "date" for calculing days. I need to calculate the
following day for any day. Doing that I see a error.

I use for example: date --date "1920-05-02 1 days" "+%F"

and for the followings days, I see a error:

date: invalid date `1920-05-01 1 days'
date: invalid date `1930-12-01 1 days'
date: invalid date `1931-10-15 1 days'
date: invalid date `1932-11-01 1 days'
date: invalid date `1933-11-01 1 days'
date: invalid date `1934-11-01 1 days'
date: invalid date `1935-11-01 1 days'
date: invalid date `1936-11-01 1 days'
date: invalid date `1937-11-01 1 days'
date: invalid date `1938-11-01 1 days'
date: invalid date `1939-11-01 1 days'
date: invalid date `1941-10-15 1 days'
date: invalid date `1943-10-15 1 days'
date: invalid date `1940-07-01 1 days'
date: invalid date `1946-10-01 1 days'
date: invalid date `1963-12-15 1 days'
date: invalid date `1964-10-15 1 days'
date: invalid date `1965-10-15 1 days'
date: invalid date `1966-10-15 1 days'
date: invalid date `1967-10-01 1 days'
date: invalid date `1968-10-06 1 days'
date: invalid date `1969-10-05 1 days'
date: invalid date `1974-01-23 1 days'
date: invalid date `1988-12-01 1 days'
date: invalid date `1989-10-15 1 days'
date: invalid date `1990-10-21 1 days'
date: invalid date `1991-10-20 1 days'
date: invalid date `1992-10-18 1 days'
date: invalid date `2007-12-30 1 days'
date: invalid date `2008-10-19 1 days'
date: invalid date `2038-01-19 1 days'

Thanks!

Sorry for my bad english

David Alejandro Gonzalez Marquez