HP-35’s x^y Why?

[Albert Chan]

(11-03-2021 03:46 AM)robve Wrote:  HP-35s:
ALG mode: (-128)^INV(7) ERROR
RPN mode: 7 1/x 128 (-) y^x ERROR

You are assuming the reason it fail is INV(INV(7)) does not revert back to 7 ?
My guess is it never even check that.

Negative number raised to non-integer exponent is a automatic fail.

Try (-128)^INV(3) instead, since INV(INV(3)) = 3 (binary or decimal, any precision)