fields with float[48] type question

Hi,

I have two pc's with PostgreSQL 6.4.2r and 6.5beta2
and some troubles with both of them.

Well, here's an example:
I create some simple table with float field (called field_one), insert
value 100 in it. Then I need to increase/decrease it number by 0.06 on
every step
many times (from trigger/SPI or simple shell script contains just _21_
(or less)
lines like this: 'update <class_name> set field_one = field_one [-+]
0.06')...
Here'we go. If I put _22+_ lines I got very interesting results. For
example:
100 - 22 times by 0.06 == 98.6799999999999 instead of 98.68... And it's
not
the end of story...

Can someone explain me such behaviour?..

--
Sergey S. Rakitin ElVisti
SSR2-RIPE Information Center