factor(x^4+1) and partfrac(1/(x^4+1))

[Aries]

(10-21-2019 02:05 PM)rombva Wrote:  HP Prime G2 (SW Ver 2.1.14181, CAS Ver 1.4.9) can't factorize the expression x^4+1. It returns this expression unchanged.

Also, partfrac(1/(x^4+1)) can't return partial fractions.

Is it a bug or a desired feature?

From my experience with TI calcs, the TI-Nspire CAS attempts to factor/expand any expression with linear, rational and real factors, the expression shown is not factorable based on these conditions:



By specifying a variable, Nspire CAS is able to produce linear factors, as long as these factors contain only real numbers.



Some polynomials are prime but, by specifying you want to factor in terms of x, you make sure Nspire produces linear factors (with approximations of irrational numbers).
Using propfrac:



I don't know if this applies to HP Prime, it's just a shot in the dark.
Best,

Aries