Re: [avr-libc-dev] Math accuracy

[Björn Haase]

David Carr wrote on Montag, 24. April 2006 09:30 :
> Just for fun I ran the "savage" benchmark on my Mega16 at 6MHz.  I
> attempted to use double precision everywhere.  (I say attempted because
> I'm no expert at this.)
>
> A further test reveals (to me) that sizeof(float) == sizeof(double) == 4.
> Is there a way to have sizeof(double) == 8?
Yes: 
You would have to write floating point emulation for 8-byte double IEEE 
numbers. So far the only thing avr-libc is having is a FP emulation for 
4-byte floats (that is IIRC not fully IEEE compliant).
Presently there is no difference concerning the code if you are writing 
"double" or "float".

Bjoern.