Faster factor finder method for 42S

[Dave Britten]

(12-02-2019 07:17 AM)Werner Wrote:  Great idea, Dave!
Can't wait to rewrite my own routine using this idea! (using only the stack, and without flags ;-)
There's a simpler way of finding out whether there's a zero in your remainders: (and no need for the matrix R)

Code:

 SF 25
 1/X
 FC?C 25
 GTO 02

Very clever! That won't tell you where in the matrix there was a zero, so you'll have to take additional steps to find it, but optimizing for the common case (i.e. no factors found) makes sense.

It's a shame that MOD won't work with matrices the same way division and 1/X will. In its current state, the matrix approach won't work with 12-digit numbers, since the fractional part will be lost with small divisors (any result where the fractional part rounds down to .0 will have the same issue).