No reason for +1, I just added it to test what I liked most and forgot to remove it (0-6 is the most common used range).

This morning I tried another slightly different version and still got the same discrepancies:

• up to some date in 2006 everything works in a different way and I get plenty wrong results
• from there on till Jan.2011 the function returns almost always correct results but on some rare occasion sunday (not the other days) is reported incorrectly

from the end of January 2011 everything works fine. I’m giving up!

Have a good day.