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Ans and ^ (1/3)
03-30-2015, 06:15 PM
Post: #3
RE: Ans and ^ (1/3)
(03-30-2015 04:08 PM)Helge Gabert Wrote:  I ran into this a while back, but didn't get around to posting

Let's say some calculation results in a negative number, like 7-8.2 = -1.2

Pressing x^y (1/3), using built-in Ans, results in one of the two complex roots of the polynomial x^3+1.2 being returned.

But . . . typing -1.2^ (1/3) results in the real root being returned.

How come this different behavior of Ans^(1/3) vis-a-vis the explicit, typed result?

CAS settings: simplify min, exact, use sqrt, principal, use i.

This inconsistency also occurs in RPN mode. It might be something to do with raising the number to the 1/3 power vs. taking the cube root. For example if I place -8 on the stack and then 1/3 on the stack and hit the x^y key I get a complex root, but if I place -8^(1/3) on the stack I get -2 after pressing eval.
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Messages In This Thread
Ans and ^ (1/3) - Helge Gabert - 03-30-2015, 04:08 PM
RE: Ans and ^ (1/3) - parisse - 03-30-2015, 06:08 PM
RE: Ans and ^ (1/3) - Helge Gabert - 03-30-2015, 08:36 PM
RE: Ans and ^ (1/3) - BartDB - 03-31-2015, 09:37 AM
RE: Ans and ^ (1/3) - Joe Horn - 03-31-2015, 09:51 AM
RE: Ans and ^ (1/3) - John Colvin - 03-30-2015 06:15 PM
RE: Ans and ^ (1/3) - Helge Gabert - 03-30-2015, 08:42 PM
RE: Ans and ^ (1/3) - toml_12953 - 04-10-2015, 06:05 PM
RE: Ans and ^ (1/3) - John Colvin - 04-10-2015, 06:34 PM
RE: Ans and ^ (1/3) - BartDB - 03-31-2015, 09:46 AM
RE: Ans and ^ (1/3) - John Colvin - 03-31-2015, 07:45 PM
RE: Ans and ^ (1/3) - Han - 03-31-2015, 08:31 PM
RE: Ans and ^ (1/3) - John Colvin - 03-31-2015, 08:41 PM
RE: Ans and ^ (1/3) - BartDB - 04-08-2015, 09:27 AM
RE: Ans and ^ (1/3) - Helge Gabert - 03-31-2015, 03:32 PM



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