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From: chl@cs.man.ac.uk (Charles Lindsey)
Newsgroups: comp.misc
Subject: Re: Julian day numbers
Message-ID: <chl.672570722@m1>
Date: 25 Apr 91 09:12:02 GMT
Article-I.D.: m1.chl.672570722
References: <41601@cup.portal.com>
Organization: Dept. Of Comp Sci, Univ. of Manchester, UK.
Lines: 12

In <41601@cup.portal.com> J_Otto_Tennant@cup.portal.com writes:

>First, why is the constant 30.6001?  JM ranges from 4 to 15.  If we
>view the constant 30.6001 as (30.6 + 0.0001), the 0.0001 term is
>completely irrelevant to the calculation.  Why, in a book as
>careful and accurate as _Numerical_Recipies_ would there be such
>an irrelevant part of a constant?

The calculation has to be performed in floating point. It may be that in
some floating point formats a number input as 30.6 gets stored as
30.5999999999999999. Looks like the extra .0001 was to make sure this didn't
happen.