(10-21-2019 11:58 AM)John Keith Wrote: The HP 50 in approximate mode and with flag -54 (the "cheat" flag) set*, returns 0 for both Dave's and Thomas's matrices. I'm surprised that the 42s gives an inexact result, I assumed the internal code for matrix math was essentially the same as the 48/49 series.

It looks like the "cheat" was added with the 48G. I just tried calculating the determinant with my 48SX, and I get the same 3.30000000001E-12 as the 42S. I don't have a 28S/C handy, but I would expect they do the same as the 42S and 48SX.