MathGroup Archive 2005

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

Search the Archive

Re: TrigExpand - Odd behavior


Bob Stagat wrote:
> Try executing the following three lines and explain the last result...
> 
> Cos[45 Degree]
> 
> Cos[x+45 Degree]
> 
> Cos[x+45 Degree]//TrigExpand
> 
> Thanks...
> ~ BS ~
> 

Hello Bob,
"Degree" has an accurate value of 180/Pi. Mathematica will not replace 
accurate expressions by expressions having machine precision. Therefore:
Sin[1 Degree]
will not evaluate, however this will:
Sin[45 Degree]
because there is a closed form accurate answer. Also the following will 
evaluate:
Sin[1. Degree]
because 1. Degree has machine precission.

Your output looks rather strange because Degree is printed by a small o. 
This may look bizare, but it still means 180/Pi.

Daniel


  • Prev by Date: categorys in the Help Browser
  • Next by Date: Re: TrigExpand - Odd behavior
  • Previous by thread: Re: TrigExpand - Odd behavior
  • Next by thread: Re: TrigExpand - Odd behavior