advantages of fused multiply-add, and a thesis project
Jon L White
uunet!lucid.com!jonl%kuwait
Tue Jun 18 12:46:30 PDT 1991
re: [Explanations: single precision rather than double in order that higher-
precision intermediates can be investigated.
If I recall correctly, the MC68881 has a Rounding-Precision state, which
can cause all rounding to be done to 32-bit format, or 64-bit format,
despite the internal 96-bit registers (80 mantissa, 16 exponent?). Some
other hardware also offers this as a "mode" option. When utilized, these
modes seem to cause a very noticeable performance degradation; so I would
suppose they exist for precisely the same purpose you are invoking here?
-- JonL --
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