Why won't the prime graph correctly?

[toml_12953]

(05-23-2019 06:21 PM)Gilles Wrote:  WolframAlpha gives the same complex result as does the HP50g, newRPL, HPPrime (in home mode,set allow complex number). There is a bug in the NSpire here

The Nspire CX CAS and Nspire CX II CAS give the complex answer if complex is turned on in settings and -1 if complex results are turned off. In real mode, -1 could be considered correct since cubing the cube root of -1 gives the original number:

((-1)^(1/3))^3 = -1

(-1)^(1/3) = -1
Ans^3 = -1