Why abs(sin(pi/n)) is not simplified by sin(pi/n) when n>2
 
  
 
  
 
 
 
 
 
 
    
        
        asked 11 years ago  
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I try to simplify an expression but Sage can't to do so.
 
This is my code :
 
sage: n= var("n")
sage: assume(n,'integer',n>2)
sage: show((abs(sin(pi/n))).simplify_full().simplify_trig())
 
But this code  :
 
sage: show((abs(pi/n)).simplify())
 
gives "of course" the good result  : 
 
pi/n
 
Can someone explain to me what is happening?
 
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Comments
The most one can say here is that Maxima doesn't "know" that sin(pi/n) is, in fact, positive.  The assumptions framework in Maxima (and hence Sage) is acknowledged to be fairly weak.
kcrisman gravatar imagekcrisman (
    
        11 years ago
    )
It is unfortunate because for more complicated expressions that simplify a lot, we can not rely on Sage for such simplification.   Thanks Krisman for your help!
moroplogo gravatar imagemoroplogo (
    
        11 years ago
    )
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