Fixpoint Atithmetic / Fractal Calculation Speedup
Torbjorn Granlund
tg at gmplib.org
Mon May 16 11:19:14 CEST 2011
Jürgen Hochwald <jh at cfjh.de> writes:
I've a self written fractal programm to calculate a zoom animation. Currently
all calculations are done with the mpf_t types.
Mpf_t means (I think) that the numers are normaisized to some internally
format after each calculation and before each addition/subtraction (like IEEE
754 for normal floating point numbers).
My thougths are to speed up the calculation when I have a fixpoint arithmeic,
where all normalisation steps are omitted.
My question: How is a fixpoint arithmetic possible (by using low level
functions) or planned?
How many speedup will this bring?
I don't think this has an easy answer.
In mpf, normalisation is usually very cheap, I believe it is O(1) for
every operation.
There is some bookkeeping needed, but I am not sure it will be easier
with fixed point.
My guess is that fixed-point will be no faster, except if you hardwire
some asm routines for some fixed number of bits.
--
Torbjörn
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