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Re: cubic root [message #83959 is a reply to message #68737]

Tue, 16 April 2013 09:44

Lajos Foldy
Messages: 176
Registered: December 2011

Senior Member

On Tuesday, April 16, 2013 5:19:00 PM UTC+2, fawltyl...@gmail.com wrote:

> (-1)^1.0/3 gives -0.333333 for me.
>
> You have to specify that you want complex roots:
>
> IDL> help, complex(-1.0)^(1.0/3)
> <Expression> COMPLEX = ( 0.500000, 0.866025)
>

Also, here is a function for the real cubic root:

function cubic_root, x
return, x ge 0 ? x^(1/3.0) : -(-x)^(1/3.0)
end

(Change 3.0 to 3.0d for double precision x.)

regards,
Lajos

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[Message index]

		Cubic root finding on a grid By: Luds on Fri, 20 November 2009 08:03
		Re: cubic root By: Lajos Foldy on Tue, 16 April 2013 09:44
		Re: cubic root By: wlandsman on Tue, 16 April 2013 08:27
		Re: cubic root By: Lajos Foldy on Tue, 16 April 2013 08:19

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