Re: Bug: date.cpp

Posted by Luigi Ballabio-3 on Dec 21, 2000; 1:15pm
URL: http://quantlib.414.s1.nabble.com/Bug-date-cpp-tp1643p1645.html

At 12:39 PM 12/21/00 +0100, Gilbert Peffer wrote:

>I found a slightly more serious bug in Date::year(), unless it was an
>intended behaviour.
>
>I think the function only works correctly (explained below what that means),
>if you calculate the year using
>
>         Year y = (theSerialNumber - 1)/365.25
>
>The function, from my point of view, should at least implement the
>year-change correctly. A little example using the 31/12/1999 and 1/1/2000
>shows that the current function doesn't and the proposed one does:
>
>     31/12/1999     resulting in     2000.0657... (current)
>                    resulting in     1999.9972... (new)
>
>     1/1/2000       resulting in     2000.0712... (current)
>                    resulting in     2000         (new)

Hi Gilbert,
         in this case

Year y = theSerialNumber/365;

only gives a first guess. The two lines below, namely,

while (theSerialNumber < yearOffset[y])
     y--;

check the correctness of the guess and set y to the right value.
I agree that

>Year y = (theSerialNumber - 1)/365.25

might be a better guess. However, I'd like to leave the check, just in case
(365.25 isn't the exact value either)

Bye,
         Luigi