On 2/24/11 5:55 AM, Steven D'Aprano wrote:
On Wed, 23 Feb 2011 13:26:05 -0800, John Nagle wrote:
The IEEE 754 compliant FPU on most machines today, though, has an 80-bit
internal representation. If you do a sequence of operations that retain
all the intermediate results in the FPU registers, you get 16 more bits
of precision than if you store after each operation.
That's a big if though. Which languages support such a thing? C doubles
are 64 bit, same as Python.
C double *variables* are, but as John suggests, C compilers are allowed (to my
knowledge) to keep intermediate results of an expression in the larger-precision
FPU registers. The final result does get shoved back into a 64-bit double when
it is at last assigned back to a variable or passed to a function that takes a
double.
--
Robert Kern
"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco
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