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Re: Parity of EllipticTheta

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  • Subject: [mg130758] Re: Parity of EllipticTheta
  • From: Bob Hanlon <hanlonr357 at>
  • Date: Fri, 10 May 2013 00:32:07 -0400 (EDT)
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Modifying built-in functions is prone to unintended consequences. Recommend
something along the lines of

etRule = EllipticTheta[1, -x_, q_] :>
   -EllipticTheta[1, x, q];

Apply the rule each time that you use EllipticTheta

EllipticTheta[1, -x, q] /.

-EllipticTheta[1, x, q]

Or if you are willing to expend the overhead, apply it automatically to all
output expressions:

$Post = # /. etRule &;

EllipticTheta[1, -x, q]

-EllipticTheta[1, x, q]

Bob Hanlon

On Thu, May 9, 2013 at 2:45 AM, Christian <christian.hagendorf at>wrote:

> Hi,
> I use quite often the functions EllipticTheta[n,x,q] in Mathematica.
> Unlike for trigonometric functions Mathematica does not simplify
> expressions of the type EllipticTheta[1,-x,q] to -EllipticTheta[1,x,q]
> automatically (it does it for Sin[-x]). How do I add such a feature to a
> built-in function?
> Thank you in advance,
> Ch.

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