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Old 2005-06-16, 20:04   #1
P90 years forever!
Prime95's Avatar
Aug 2002
Yeehaw, FL

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Default New factoring breakeven points coming

Coming in the final version of 24.12 are new trial factoring breakeven points!!

#define FAC72 96830000L
#define FAC71 75670000L
#define FAC70 58520000L
#define FAC69 47450000L
#define FAC68 37800000L
#define FAC67 29690000L
#define FAC66 23390000L

These were calculated on my 2.0 GHz P4. They are much, much higher than before. That is, we will be doing a lot less trial factoring in the future.

There are several reasons these are higher.

The old breakeven points were probably done on my 400 MHz PII. With SSE2 and the P4's fast L2 cache and lots of coding tweaks, LL tests are now a lot faster relative to factoring. That is, a new factor doesn't save as much LL time as it used to.

Also, I've assumed a missed trial factor will be found by P-1 factoring 30% of the time. P-1 factoring didn't even exist when the old breakeven points were calculated.

For comparison, the old breakevens were:

#define FAC72 71000000L
#define FAC71 57020000L
#define FAC70 44150000L
#define FAC69 35200000L
#define FAC68 28130000L
#define FAC67 21590000L
#define FAC66 17890000L
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