Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2005
*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 2005

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

Search the Archive

ExpToTrig with Real Numbers

  • To: mathgroup at smc.vnet.net
  • Subject: [mg63334] ExpToTrig with Real Numbers
  • From: "Blimbaum, Jerry CIV NSWC PC" <jerry.blimbaum at navy.mil>
  • Date: Sat, 24 Dec 2005 07:18:59 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com
  • Thread-index: AcYH+AuI2LVNWa4RRYe/xe7Lw23ALg==

A calculation gives me the following as a part of the output that I see
on the screen: (i = Imaginary)

-0.262484 i  Exp[-0.951249 i t] +   0.262484 i Exp[0.951249 i t]

I want to apply ExpToTrig and , of course, end up with 0 for the Cosine
part and - .262484*2  Sin [0.951249] for the Sine part ...

instead I get  (which I decided to look at output with InputForm)

(-0.2624844042359744*I)*Cos[0.9512492197250393*t] +
(0.26248440423597375*I)*Cos[0.9512492197250397*t] -
 0.2624844042359744*Sin[0.9512492197250393*t] -
0.26248440423597375*Sin[0.9512492197250397*t]

I can see from this that the coefficients and exponent numbers are very
close but not identical  although , I think, in theory they should be.
I'm not worried about the 10th decimal place.    How do i get the result
I want in a general way?


thanks....jerry blimbaum



  • Prev by Date: Re: Matrices with Mathematica 5.1
  • Next by Date: RealValued functions and derivatives
  • Previous by thread: Re: Re: Questions regarding MatrixExp, and its usage
  • Next by thread: Re: ExpToTrig with Real Numbers