[PPL-devel] Fwd: PPL and FPU rounding mode

[Benjamin Hiller]

Hello PPL developers,

continuing a discussion I had with Prof. Bagnara:

Am 10.08.2011 21:38, schrieb Roberto Bagnara:
>> Am 10.08.2011 18:38, schrieb Roberto Bagnara:
>>> If you call restore_pre_PPL_rounding() reset the rounding mode to its
>>> default (typically round-to-nearest) AND you use a PPL abstraction
>>> based on floating point numbers without first calling
>>> set_rounding_for_PPL() then the result computed by PPL will be bogus.
>>> For example, you may have a non-empty box be mistaken for empty. Of
>>> course, you may be lucky, but I would not count on that.
>>
>> Our data should be such that each polyhedron is far from being
>> degenerated so I don't think they will become empty due to rounding.
>>
>>> Which PPL classes are you using? Many PPL classes are not based on
>>> floating point numbers. If you only use those, then there is no problem
>>> at all, whatever rounding mode is in effect.

Where in the documentation can I find the information which
classes/operations are safe to use (ie not based on floats) without
rounding and which not? I skimmed the online docs and was not able to
figure this out myself.

Best regards,

Benjamin
-- 
Benjamin Hiller                                           hiller at zib.de
Abteilung Optimierung                            phone +49 30 84185-406

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