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Diffstat (limited to 'TODO')
| -rw-r--r-- | TODO | 18 |
1 files changed, 0 insertions, 18 deletions
@@ -491,24 +491,6 @@ Table of contents: * In debug mode, MPFR would check that the result is exact (i.e. that the ternary value is 0). -- new "rounding mode" MPFR_RNDF (faithful rounding)? - This is not really a rounding mode since it is non-deterministic. The - goal is to avoid the Table Maker's Dilemma in internal computations. - The definition of faithful rounding of a real number x is: return either - RNDD(x) or RNDU(x). This means that if x is exactly representable, one - returns x exactly. In MPFR, the ternary value should be unspecified for - efficiency reasons. - Note: One typically implements faithful rounding by computing an - approximation to the result with some adequately chosen error bound, - then by rounding this approximation to nearest. - Concerning the choice of the error bound, if the result x is equal to - 1 + t, where t is a very small positive number, then the error bound - needs to be at most ulp(x)/4 + t. Since t can be arbitrarily small, - the error bound needs to be at most ulp(x)/4. And this error bound - is sufficient in all cases. Note that with the even rounding rule or - rounding away from zero, it is not needed to relax the condition when - x is exactly representable. - - add tests of the ternary value for constants - When doing Extensive Check (--enable-assert=full), since all the |