[development] Converting floats stored in scientific notation back to decimals

Walt Daniels wdlists at optonline.net
Mon Nov 5 19:06:45 UTC 2007

decimal numbers do not an exact binary representation (in general), e.g.
1/3, within the finite field width of computers. Any time you convert you
have rounding issues which are messy at best. If your meaning of decimal
numbers is really just dollars and cents (not internationalizable) with 2
decimal places, then you should use integers (in cents) and then you just
have a formating problem. 

-----Original Message-----
From: development-bounces at drupal.org [mailto:development-bounces at drupal.org]
On Behalf Of Karen Stevenson
Sent: Monday, November 05, 2007 1:59 PM
To: development at drupal.org
Subject: Re: [development] Converting floats stored in scientific notation
back to decimals

Are you going to use something big, such as decimal(64,32)? Or are you
looking for a conversion which preserves the most significant digits up to
some point? How many decimal digits do you have in mind?

Perhaps I don't understand this correctly, but storing the values as
decimals looks like trouble to me.

Changing from a float column to a decimal column is an issue that was very
important to a lot of people and I'm trying to make that happen. I am
assuming that a decimal field with two decimals would be the type of column
people would expect for the CCK decimal field, but I don't know for sure
what size or precision would be best.

Anyway, what I'm really trying to do is find a volunteer familiar with and
interested in getting a real decimal field in CCK who can figure out what is
needed and create a patch for this. I'm trying to get the D6 port done and
don't have time to do it. If I do spend time doing it, it will delay getting
CCK ported to 6x.



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