Subject RE: [firebird-support] Double precision field problem
Author ibrahim bulut
This problem does not happen all the records

Generally records are ok, but some records have problem

When i change the field's value manuel (with ibconsole)

Problem still occurs

Field1's value is exactly 79.69 and

Field2's value is exactly 78.12

because i have changed them manually

but result is not exact value


[] On Behalf Of Svein Erling Tysvaer
Sent: Monday, October 30, 2006 2:51 PM
To: Firebird-support
Subject: Re: [firebird-support] Double precision field problem

You get what you ask for, Ibrahim. Floating point numbers (e.g. double
precision) are good for measuring things, it doesn't matter whether the
length of a line is 1.57 metres or 1.5699999999999 metres. Field1
doesn't have the exact value 79.69, it has a value of approximately
79.69 (e.g. 79.69000000000000001238) and similar for Field2.

If such differences do matter, you should probably use fixed point
numbers - e.g. decimal or numeric.


ibrahim bulut wrote:
> i am in trouble double precision field with subtract operation
> field1 is double precision
> field2 is double precision
> field1's value is 79.69
> field2's value is 78.12
> when i subtract field2 from field1 with this sql statement
> select field1 - field2 from table1
> the result is 1,56999999999999
> the result must be 1,57
> what is the problem
> ibrahim bulut
> software and database expert
> iletisim online ltd.sti.
> turkish republic

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