[Gretl-users] Re: Negative numbers to fractional powers
On 12/08/2020, 23:45, "Sven Schreiber" <svetosch(a)gmx.net> wrote:
Am 12.08.2020 um 19:12 schrieb Alecos Papadopoulos:
Let X be a series of negative numbers. Then the command
series Y = X^(1/3)
(or any other "1/oddnumber" fractional power)
returns a "Warning: pow: Domain error" message, overwrites series
"Y"
and returns a "no valid values" if one attempts to view the series.
Why is this happening, considering that X^(1/3) is a real number even if
X is a negative number?
Good question. I'm noticing that 'eval -1^(1/3)' works fine, in
contrast.
--> I guess that's because exponentiation takes precedence over negation. 'eval
(-1)^(1/3)' results in NaN.
All the best
Jan