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Re: Parity of EllipticTheta

• To: mathgroup at smc.vnet.net
• Subject: [mg130758] Re: Parity of EllipticTheta
• From: Bob Hanlon <hanlonr357 at gmail.com>
• Date: Fri, 10 May 2013 00:32:07 -0400 (EDT)
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• References: <20130509064506.8623F6A10@smc.vnet.net>

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] /.
 etRule


-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 gmail.com>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.
>
>

• References:
  • Parity of EllipticTheta
    • From: Christian <christian.hagendorf@gmail.com>