List:General Discussion« Previous MessageNext Message »
From:Tobias Rischer Date:April 21 1999 8:31am
Subject:Re: bc math support in MySQL?
View as plain text  
On fixed point numbers, it was said that:

> Essentially, this should be implemented simply as an integer, with an
> automatic scale on the IO routines.
> 
> Alternatively, simply use an integer, and do the scaling in your
> middleware! ;)

Just to keep people from stumbling, I'd like to add: 

This is good advice, as long as the only calculations done on the
integers *as integers* (e.g. in a SELECT expression) are + and -
operations.  It will wonderfully fail for "<fixed> * <fixed>" or
"<fixed> / <fixed>"; these operations need to know about the implied
scaling.

It is ok to do "<int> * <fixed>", "<fixed> / <int>" etc.

	Tobias


Personal Statement: 

I like the idea of fixed point numbers as the underlying data type for
DECIMAL(m,n) [or was it NUMERIC?], maybe even a BCD type.  

I'm not much of a business man, but even I wouldn't like my bank to
arbitrarily toggle the last digits of my bank account and explain that
with floating point anomalies caused by the exact sequence of my earning
and spending money. (I can almost see them telling me I should never
look for exact equality in an account balance, but rather use some
appropriate Epsilon!  :-)

-- 
.............................................
       (_)                     Tobias Rischer
        "==='              tobias@stripped
         " "
...still.loving.gnu..........................
Thread
bc math support in MySQL?jkraai20 Apr
  • Re: bc math support in MySQL?Jules Bean20 Apr
    • Re: bc math support in MySQL?Tobias Rischer21 Apr
      • Re: bc math support in MySQL?Tobias Rischer21 Apr
    • Re: bc math support in MySQL?Tobias Rischer21 Apr
      • Re: bc math support in MySQL?Jules Bean21 Apr
    • Re: bc math support in MySQL?Fred Read21 Apr
Re: bc math support in MySQL?jkraai20 Apr