REAL 64 (issues)
This page describes issues with the current implementation of REAL_64 in comparison to the interace description.
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.