On 2009-Dec-29 23:29:42 +0000, "Dr. David Kirkby" <david.kir...@onetel.net> wrote: >There are a few failures, but these couple just came up, and look >rather odd, as this is only an error in the last decimal place, and >so will be subject to rounding errors with different floating point >processors. They do not really seem failures to me.
One of the claims for IEEE-754 arithmetic is that basic arithmetic operations (+, -, *, /, sqrt) will give bit-for-bit identical results on different implementations. >********************************************************************** >File "/rootpool2/local/kirkby/sage-4.3/devel/sage/sage/symbolic/pynac.pyx", >line >1276: > sage: py_exp(float(1)) >Expected: > 2.7182818284590451 >Got: > 2.7182818284590455 >********************************************************************** As a correctly rounded IEEE-754 double precision constant, e=0x4005BF0A8B145769 (0x2.B7E1 5162 8AED 2), this should convert to 2.7182818284590451 (rounded to "sufficient" accuracy). 2.7182818284590455 is 1ULP high - this may reflect a rounding error in either the exp() or double_to_ascii() implementation. -- Peter Jeremy
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