--- In firebird-support@yahoogroups.com, "ibrahim bulut" <i.bulut@...>
wrote:

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> i am in trouble double precision field with subtract operation
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> field1 is double precision
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> field2 is double precision
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> field1's value is 79.69
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> field2's value is 78.12
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> when i subtract field2 from field1 with this sql statement
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> select field1 - field2 from table1
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> the result is 1,56999999999999
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> the result must be 1,57
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> what is the problem

Double Precision is a floating point style number type, not a numeric.
This behaviour is perfectly normal for the datatype you are using. The
problem is you are expecting numeric behaviour.

Read the following article:

http://en.wikipedia.org/wiki/Floating_point

Particularly point 9 (4 is also useful).

Adam