Easy question

[ijabbott]

(09-10-2021 05:23 PM)Albert Chan Wrote:  

(09-09-2021 11:59 PM)ijabbott Wrote:  The result of (-1)^(4/5) will depend on whether or not you have the "Allow complex output from real input" option turned on or off in the settings. If turned off, you will get the real result -1. If turned on, you will get the complex result -0.809016994375+0.587785252292*i. Also, I think the CAS mode always approximates to the complex result.

HP Prime emulator, 2.1.14181 (2018_10_16), just after a hard reset.

From Symbolic Setup, if I pick Complex: Off, (-1)^(4/5) gives -0.809016994375+0.587785252292*i.
If I pick Complex: System, or On, (-1)^(4/5) give "Error: (X<0)^(∉Z)"

I was unable to setup calculator to give real root for (-1)^(4/5) = 1.0

On my real HP Prime G1 2.1.14588 (2021_05_05), setting Complex: On in Home Symbolic Settings produces a real result = 1, and setting Complex: Off produces the aforementioned complex result. That seems to be opposite of what I expected. It may be a bug?

The "Intelligent Math" option in Home Settings needs to be turned off for all of the above.

Setting Complex: On and evaluating (-1)^.8 produces the domain error that Albert mentions.