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littleHilbert
Oct2-08, 12:34 PM
Hi! Brief question:

I wonder which conditions should a polynomial function of odd degree fulfill in order to be symmetric to some point in the plane.
Are there such conditions?

Gib Z
Oct4-08, 12:19 AM
Of course there are! It's merely horizontal and vertical translations of the ordinary condition for an odd function, which is symmetric about (0,0).

For symmetry around (0,a) a function must satisfy:

a - f(x) = f(-x) - a

For symmetry around (b,0), f(b+x) = - f(b-x).

Perhaps you can combine these conditions?

littleHilbert
Oct5-08, 07:18 AM
Ok the combination is clear:
-f(b-x)+a=f(b+x)-a

Thank you! :-)

Gib Z
Oct5-08, 07:25 AM
you meant a + f(x) = - f(-x) - a, didn't you?
because it must be equivalent to a + f(x) + a - f(x) = 0

Ok the combination is clear:
-f(b-x)+a=f(b+x)-a

Thank you! :-)

Now that you bring it up, im not sure what I meant lol. Its something like that, though im sure its NOT equivalent to the condition a=0 lol.

littleHilbert
Oct5-08, 07:31 AM
Ok the combination is clear:
-f(b-x)+a=f(b+x)-a

Thank you! :-)

Oh sorry I've realised that everything is ok at the very moment you've sent your post...and deleted the thing!

Gib Z
Oct5-08, 07:32 AM
No problem =]