Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
1997
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 1997

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

Search the Archive

Re: trig expansion

  • To: mathgroup at smc.vnet.net
  • Subject: [mg8913] Re: [mg8854] trig expansion
  • From: Allan Hayes <hay at haystack.demon.co.uk>
  • Date: Thu, 2 Oct 1997 22:57:07 -0400
  • Sender: owner-wri-mathgroup at wolfram.com

murray at math.umass.edu (Murray Eisenberg)
[mg8854] trig expansion

> How can I cause Mathematica to expand
> 	Sin[2 Pi omega t + 2 Pi delta],
> where delta and omega are symbols, into the form
>
> Cos[2 Pi delta] Sin[2 Pi omega t]+Sin[2 Pi delta] Cos[2 Pi omega t]
>
> without using a replacment rule
>
>    Sin[a_ + b_] -> Sin[a]Cos[b] + Cos[a]Sin[b]

Murray,
Here are four inelegant ways.

(Sin[2 delta \[Pi]+2 omega \[Pi] t]/. 2->k//TrigExpand)/.k->2

(Sin[x+y]//TrigExpand)/.{x->2 Pi omega t,y->2 Pi delta}

ReleaseHold[TrigExpand[Map[Hold,Sin[2 Pi omega t + 2 Pi delta],{2}]]]

Block[{Identity},
   TrigExpand[Map[Identity,Sin[2 Pi omega t + 2 Pi delta],{2}]]
]


Allan Hayes
hay at haystack.demon.co.uk
http://www.haystack.demon.co.uk/training.html
voice:+44 (0)116 2714198
fax: +44 (0)116 2718642
Leicester,  UK


  • Prev by Date: clearing variables
  • Next by Date: RE: := vs. =
  • Previous by thread: Re: trig expansion
  • Next by thread: Re: trig expansion