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From: | dastew |
Subject: | RE: What does power operator ^ returns? |
Date: | Mon, 19 Oct 2009 19:17:52 +0000 |
> From: address@hidden > Subject: What does power operator ^ returns? > Date: Mon, 19 Oct 2009 16:42:06 +0000 > To: address@hidden > > Hi all! > > I need to compute the cubic root of many negative numbers. My problem > is real-valued, hence I am not interested in the imaginary solutions. > However, if I use the power operator '^', Octave returns just the > first imaginary solution. The same applies when doing any odd root. > > Example: > octave> a=-8 > a = -8 > octave> a^(1/3) > ans = 1.000000000000000e+00 + 1.732050807568877e+00i > > How can I make octave to return the real solution, which in my example > is just -2? I do not want just the absolute value (i.e. abs(a^(1/3)), > since it does not preserve the sign. I could do with a check on the > sign, but it would be inefficient. > > I am using Octave 3.2.3 on Mac Os X 10.6. > > Thank you very much, > > Guido > _______________________________________________ > Help-octave mailing list > address@hidden > https://www-old.cae.wisc.edu/mailman/listinfo/help-octave if you want to see all the roots try roots([1 0 0 8]) that will give you all the cube roots of -8 and roots([1 0 0 0 0 8]) will give you all 5, fifth roots of -8 :-) Doug |
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