Re: plotting even function

[Thomas Shores]

Postscript to my earlier comment: try this
octave:44> x=-1:.04:1;
octave:45> y = 3/4*(2*x).^(2/3)+1/2;
octave:46> plot(x,y)
octave:47> hold on
octave:48> plot(x,real(y))
octave:49> plot(x,imag(y))

and it will be clear what you're seeing.

Tom Shores

On Sunday 20 March 2005 01:20 am, Geraint Paul Bevan wrote:
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> John B. Thoo wrote:
> | Hi.  I hope that I'm not embarrassing myself by asking the
> | following.
> |
> | I believe that
> |
> |        3       2/3    1
> |   y = --- (2 x)    + ---
> |        4              2
> |
> | is an even function, yet
> |
> | x = -1:0.04:1;
> | plot (x, 0.75 * (2 .* x).^(2 / 3) + 0.5)
> |
> | is not symmetrical about the y-axis.  What is wrong with my
> | thinking?
> |
> | TIA.
> | ---John.
>
> x^(2/3) is not an even function,
>
> octave:1> [ (+8)^(2/3) ; (-8)^(2/3) ]
> ans =
>
> ~    4.0000 + 0.0000i
> ~   -2.0000 + 3.4641i
>
> so nor is the function which you are plotting.
>
> - --
> Geraint Bevan
> http://homepage.ntlworld.com/geraint.bevan
>
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