Comparisons with zero on HP-65

[Dieter]

(08-30-2017 09:08 PM)Mark Hardman Wrote:  DSZ only skips 2 steps if the value in R8 is exactly zero after being decremented by 1.

OK, that's something I did not know. The HP67 skips one step if INT(RI) is zero.
So your method is a X≠0? test. It turns a zero into 1 which is then decremented to zero again and DSZ skips.

Or maybe it's more like a X~=0? test:

(08-30-2017 09:08 PM)Mark Hardman Wrote:  After posting I realized that there are underflow conditions that will result in e^x returning a value of exactly 1. Results of e^x where -1e-11 <= x <= 1e-10 will also return exactly 1.

So the method tests whether e^x rounds to 1 or not.

Dieter