le 2001/07/31 00:00, Ashley Butterworth à macbse@... a écrit :

> Thanks Staz, but I really need the speed of FB^3. As I write this and FB^3
> prog is running in the background generating all of the primes up to the limit
> of a long variable and it is checking approximatley 25000 numbers every 30
> seconds, running on my 500Mhz iBook.

Although there are some tricks for going faster in certain calculations, the
basic approach to dealing with 'very long numbers' is to cut them into
smaller blocks [4 bytes?] and deal with them one after the other, taking
care to look at things like carries.

tricks for speed include:
- trying to determine if you can reduce something to division by or
multiplication by powers of two, then you can 'slide' numbers up and down
pretty quickly,
- persuading mr r purves sir to become interested in your project :-)

hth
<:-j

[wearing spikey cap so that no one can tell if i've been flatten or not!]