RE : [mg94405] branch of (-1)^(1/3)
- To: mathgroup at smc.vnet.net
- Subject: [mg94444] RE : [mg94405] branch of (-1)^(1/3)
- From: "Jaccard Florian" <Florian.Jaccard at he-arc.ch>
- Date: Sun, 14 Dec 2008 07:33:18 -0500 (EST)
- References: <200812121154.GAA27892@smc.vnet.net>
You could for example create you n-th root function :
myNthRoot[x_,n_]:=Piecewise[{{x^(1/n),x>=0},{-(-x)^(1/n),x<0}}]
Or :
myNthRoot[x_,n_]:=x/.ToRules[Reduce[y^n==x,y,Reals]]
An then :
myNthRoot[-1,3] will give you -1 like you expect.
Regards,
F.Jaccard
________________________________
De: slawek [mailto:human at site.pl]
Date: ven. 12.12.2008 12:54
=C0: mathgroup at smc.vnet.net
Objet : [mg94405] branch of (-1)^(1/3)
Is a simple way to choose the branch of (-1)^(1/3) ?
Mathematica gives a (correct) non-real answer. It is ok, but I need the =
(-1)
as the output when I input (1)^(1/3) because I know that it is a =
solution
of real-valued problem.
Is any "standard way" to pick up a correct (i.e. arbitrary) root of
(-1)^(1/n) instead the default?
slawek
- References:
- branch of (-1)^(1/3)
- From: "slawek" <human@site.pl>
- branch of (-1)^(1/3)