Hi,
You forgot to put the parenthesis in the way Petr told you :
(-6.108576e-05)^(1/3) and the result is NaN. What do you want to preserve?
Alain
carol white wrote:
but with complex, I get complex numbers for the first and last elements:
(as.complex(tmp))^(1/3)
[1] 0.01969170+0.03410703i 0.03478442+0.00000000i 0.03285672+0.00000000i
[4] 0.08950802+0.00000000i 0.05848363+0.10129661i
whereas for the first element, we get the followings.
Moreover,
-6.108576e-05^(1/3)
[1] -0.03938341
and
-(6.108576e-05^(1/3))
[1] -0.03938341
and
-((6.108576e-05)^(1/3))
[1] -0.03938341
give the same results.
so using () doesn't preserve any thing
--- On Mon, 11/16/09, Petr PIKAL <[email protected]> wrote:
From: Petr PIKAL <[email protected]>
Subject: Odp: [R] ^ operator
To: "carol white" <[email protected]>
Cc: [email protected]
Date: Monday, November 16, 2009, 3:40 AM
Hi
AFAIK, this is issue of the preference of operators.
[email protected]
napsal dne 16.11.2009 11:24:59:
Hi,
I want to apply ^ operator to a vector but it is
applied to some of the
elements correctly and to some others, it generates
NaN. Why is it not
able to
calculate -6.108576e-05^(1/3) even though it exists?
tmp
[1] -6.108576e-05 4.208762e-05
3.547092e-05 7.171101e-04
-1.600269e-03
tmp^(1/3)
[1] NaN 0.03478442
0.03285672 0.08950802 NaN
This computes (-a)^(1/3) which is not possible in real
numbers. You have
to use as.complex(tmp)^(1/3) to get a result.
-6.108576e-05^(1/3)
[1] -0.03938341
this is actually
-(6.108576e-05^(1/3))
Regards
Petr
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--
Alain Guillet
Statistician and Computer Scientist
SMCS - Institut de statistique - Université catholique de Louvain
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