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Re: Missing functions tanPi, asinPi and acosPi
Michel Hack a écrit :
I checked several 754R drafts all the way back to P754/D0.15.3 of
October 2005, where the transcendental function section was still
marked "New". Initially, the set of trig functions were those
where correctly-rounded versions existed (at least for Binary64),
namely sinPi, cosPi, atanPi and sin, cos, atan. There was a
comment from Vincent that the inverses asin, acos and tan were
also "feasibly correctly rounded", so by April 2006 (possibly
earlier) those were added to the list.
All the trigpi and inverses are definitely feasible, and actually all
implemented in crlibm (with various levels of quality though).
Exceptional cases are not even conflictual.
I seem to remember that Christoph and I noticed that they were missing a
long time ago, but at the time we had already decided to push for the
removal of the table altogether and its replacement with a more general
specification applying to arbitrary functions, and matching this table.
This suggestion was obviously rejected, and then we neglected to examine
the table again. Mea culpa.
They should definitely be added.
Florent
Nobody ever mentioned tanPi, asinPi and acosPi since then, until
now. Could it be that they were thought to be easily-derivable
from the others? Perhaps they are -- except for single-rounding
of the result...
So we need input from Vincent, Jean-Michel etc.
Michel.
Sent: 2008-04-11 15:13:39 UTC