Unexpected result calculating the determinant of a singular matrix (42S)

[Thomas Okken]

(10-21-2019 04:46 PM)Claudio L. Wrote:  

(10-21-2019 03:06 PM)Thomas Okken Wrote:  (Free42 Binary does not return zero, so the fact that Free42 Decimal does is apparently just a coincidence, not the result of a better algorithm. There is no "tiny element is zero" cheat in play either way.)

May or may not be a coincidence. There are division-free decomposition algorithms that preserve integers, so if an integer matrix is given, all operations remain integer up until the end. I don't know if this is the case for Free42 or the 48g, I know it is the case with newRPL.

Free42 does not use a division-free algorithm, that's why I said getting zero for Dave's example was a coincidence. Free42 Decimal and Free42 Binary use the same algorithm, but one returns zero and the other does not. The only difference between the two is the floating-point system used.