MathGroup Archive 2003

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

Search the Archive

Re: Domain of Sin[ArcSin[x]] ?


Hi,

Plot[(y = ArcSin[x]; If[Head[y] === Complex, 0, Sin[y]]), {x, -2, 2}]

Regards
  Jens

Michael Buescher wrote:
> 
> I want to demonstrate to my students that in the real number system,
> Sin[ArcSin[x]] is only defined on [-1,1] because that is the domain of
> ArcSin[x].  When I Plot the composition, however, I get Sin[ArcSin[x]] =
> x for all real numbers, not just on [-1,1].  I tried this both with and
> without the RealOnly package.
> 
> Is there any way to ensure that Mathematica uses only real numbers in
> its calculations, so that Sin[ArcSin[x]] is undefined when ArcSin[x] is
> not a real number?
> 
> Michael Buescher
> Hathaway Brown School


  • Prev by Date: Re: Integration of Exp[-x^2]/(1 + Exp[a * x])
  • Next by Date: Re: FrontEnd InserChar
  • Previous by thread: Re: Domain of Sin[ArcSin[x]] ?
  • Next by thread: Re: Domain of Sin[ArcSin[x]] ?