REAL 64 (issues)

Revision as of 09:42, 17 November 2006 by Juliant (Talk | contribs)

This page describes issues with the current implementation of REAL_64 in comparison to the interace description or desired output when nothing is specified.

is_equal and NaN

The floating point standard says that 'NaN = NaN' is false. But in order to uphold the postcondition of 'NaN.twin' which says that 'Result.is_equal (Current)' the comparision with 'is_eqaul' should yield true.

At the moment 'is_equal' for reals is optimized in the compiler and is replaced by '=' and thus the postcondition of 'twin' is violated.

floor, ceiling, rounded and truncated_to_integer

Currently when doing a 'floor', 'ceiling', 'rounded' or 'truncate_to_integer' with a number which is too large (e.g. 2^31) the result is {INTEGER}.min_value.

The change in the sign is a not expected behaviour and violates (informal) contracts.

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