x’ forecast only on HP-32E

[brouhaha]

(06-20-2023 12:56 PM)Dave Britten Wrote:  I always thought it was kind of odd they included it on the 12C but not the 11C or 15C.

"Life is short and ROM is full."
- Bill Wickes

But also there aren't extra key assignments available on the 11C and 15C. That's why the 15C had to move all but two of the number comparisions into "g TEST <n>" sequences.

It's easy enough to write a subroutine to do it on the 11C and 15C. Swap two pairs of statistics registers (R3 with R5, R4 with R6), compute the y linear estimate, swap back. On the 15C this can be fairly conveniently done in the subroutine without disturbing the stack with a sequence of "x <>" instructions.