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Authored by: Anonymous on Friday, May 04 2012 @ 02:39 PM EDT |
Most recent CPU designs include 4-way SIMD hardware instructions for square root
or estimated square root, estimated reciprocal square root, and estimated
reciprocal. Some of them also include 3- and 4-way dot product instructions
(which are very useful for all sorts of linear algebra things, like measuring
the length of vectors... anyway, it comes up a lot in game development)[ Reply to This | Parent | # ]
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Authored by: mschmitz on Friday, May 04 2012 @ 07:16 PM EDT |
Most recent CPUs or FPUs apparently no longer conform to the IEEE 754 standard -
I've long observed differences in MD simulation results from identical inputs,
run on different processor architectures. Even variants of the Intel x86
processors. Single precision may be OK, double precision does seem to vary.
So even though double cos(double) is the expected natural API, and has to be
retained (as it should be), implementations differ even in hardware (where they
rather should not, at least in respect to the outcome).
But thinking of IEEE 754 raises a point regarding the API: the names of the
floating point functions are mandated by the standard (there's the API again).
-- mschmitz
[ Reply to This | Parent | # ]
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