Derivatives on HP 42S

[Thomas Klemm]

You can still deliberately choose the other branch that makes the result real for negative input:

Code:

LBL "Fx"
RCL ST X
+/-
3
1/X
Y↑X
+/-
X<>Y
4
+
*
END

With initial guesses -4 and 0 you get what you expected:

x=-1

But now the function returns complex values for positive input.

Kind regards
Thomas