Services & Resources / Wolfram Forums / MathGroup Archive

MathGroup Archive 2012

[Date Index] [Thread Index] [Author Index]

Search the Archive

TrigReduce: controlling the scope

  • To: mathgroup at
  • Subject: [mg129061] TrigReduce: controlling the scope
  • From: alan <alansbarnett at>
  • Date: Tue, 11 Dec 2012 02:25:05 -0500 (EST)
  • Delivered-to:
  • Delivered-to:
  • Delivered-to:
  • Delivered-to:

I have an expression that is a sum of products of trignometric functions. Each term is something like this:
Sin[alpha] Cos[omega tau1] Cos[omega tau2] Cos[beta].                  (1)
I want to apply trig identities to the terms that contain omega to transform them into trig functions of sums and differences, but I don't want the same transformation applied to the terms involving alpha and beta.  For example, I want to express (1) as
(1/2) Sin[alpha] Cos[beta](Cos[omega(tau1 - tau2)]+Cos[omega(tau1 + tau2)])

If I apply TrigReduce to (1), I get terms like
Cos[omega tau1 - omega tau2 + alpha - beta].
How do I restrict the action of TrigReduce to terms containing omega?
(I can do a hybrid calculation by cutting and pasting the terms I want, but I'd rather not have to cut and paste by hand).


  • Prev by Date: Re: Mathematica for windows crash
  • Next by Date: Dynamic Table
  • Previous by thread: Re: Mathematica 9 does not read mathematica 8 ".mx" files
  • Next by thread: Re: TrigReduce: controlling the scope