[Date Index]
[Thread Index]
[Author Index]
Re: trig expansion
*To*: mathgroup at smc.vnet.net
*Subject*: [mg8933] Re: trig expansion
*From*: Paul Abbott <paul at physics.uwa.edu.au>
*Date*: Sat, 4 Oct 1997 22:08:10 -0400
*Organization*: University of Western Australia
*Sender*: owner-wri-mathgroup at wolfram.com
Murray Eisenberg wrote:
> 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]
>
> explicitly?
What is wrong with using a replacment rule? It is probably the best way
to achieve what you want here.
I assume that this question is related to your earlier question (which I
assume is related to Fourier series expansions?):
>I want to make an assignment T = k/omega and somehow cause Mathematica
>to know that k is an integer. How do I do this?
In my opinion, the best way to is using pattern-matching and replacement
rules (see The Mathematica Journal 2(4): 31). E.g., for n integral, we
have
{Cos[(n_)*Pi] -> (-1)^n, Sin[(n_)*Pi] -> 0};
Cheers,
Paul
____________________________________________________________________
Paul Abbott Phone: +61-8-9380-2734
Department of Physics Fax: +61-8-9380-1014
The University of Western Australia
Nedlands WA 6907 mailto:paul at physics.uwa.edu.au
AUSTRALIA http://www.pd.uwa.edu.au/~paul
God IS a weakly left-handed dice player
____________________________________________________________________
Prev by Date:
**Re: Piecewise functions**
Next by Date:
**Help! Sin[n Pi] (n Integer)**
Previous by thread:
**Re: trig expansion**
Next by thread:
**Re: trig expansion**
| |