Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2001
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2001

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

Search the Archive

Re: AW: Re: Expanding Trig Power Identities

  • To: mathgroup at smc.vnet.net
  • Subject: [mg30402] Re: AW: [mg30365] Re: [mg30348] Expanding Trig Power Identities
  • From: BobHanlon at aol.com
  • Date: Wed, 15 Aug 2001 01:04:08 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

In a message dated 2001/8/14 8:44:10 AM, Matthias.Bode at oppenheim.de writes:

>I tried Bob Hanlon's TrigReduce Table changing n from "{n, 4}" to "{n,
>1, 3,
>0.5}":
>
>Table[{y = Sin[a]*Sin[b]^n, "=", TrigReduce[y]}, {n, 1, 3, 0.5}] //
>TableForm
>
>and neither the integer nor the non-integer exponent expressions evaluated
>whereas the original example "{n, 4}" evaluates just fine. Why?
>

If the step is an approximate number then everything after the first value 
(even if it is exact) is approximate.

Table[k, {k, 1, 3, 0.5}]

{1, 1.5, 2., 2.5, 3.}

The TrigReduce rules require certain forms (exact powers).  Use an exact 
(rational) step

Table[{y = Sin[a]*Sin[b]^n, "=", TrigReduce[y]}, 
      {n, 1, 3, 1/2}] //Factor // TableForm

or

Table[{y = Sin[a]*Sin[b]^Rationalize[n], "=", TrigReduce[y]}, 
      {n, 1, 3, 0.5}] //Factor//TableForm


Bob Hanlon
Chantilly, VA  USA


  • Prev by Date: Axes label rotation
  • Next by Date: AW: Re: Expanding Trig Power Identities
  • Previous by thread: Axes label rotation
  • Next by thread: AW: Re: Expanding Trig Power Identities