Maxima 5.9.3 bug in limit, not really



You could contribute to getting a better answer than "ind", perhaps
the right answer or perhaps returning the limit as unevaluated, 
by writing another program. e.g. vblimit(...) := ....

For a start,  vblimit(a,b,c):= limit(trigsimp(a),b,c);

Another possibility is 
  vblimit(a,b,c):=block([ans:limit(a,b,c)], if (ans=ind) then 'limit(a,b,c)
else ans);


 

> -----Original Message-----
> From: maxima-bounces at math.utexas.edu 
> [mailto:maxima-bounces at math.utexas.edu] On Behalf Of Vladimir 
> Bondarenko
> Sent: Sunday, August 27, 2006 9:00 AM
> To: maxima at math.utexas.edu
> Cc: Richard Fateman
> Subject: Re: [Maxima] Maxima 5.9.3 bug in limit, not really
> 
> Hello,
> 
> 1. I fully agree with you that
> 
> RJF>  It is a difficult engineering question to figure  out how much 
> RJF> work to do on simplifying input  without special requests, like 
> RJF> trigsimp.  If you  do too much, commands can take too much time.
> 
> I would even say, "It is a very difficult engineering question"
> 
> 2. I could agree with you - if Maxima would return the
>    input unevaluated. Well... the system just cannot do
>    it.
> 
>    However, in the given case, Maxima returns an answer
>    which is mathematically incorrect, namely,  ind.
> 
> 3. Some other system handles this successfully, say, any
>    version of Derive since 1980 to 2006, and Mathematica,
>    at least MMA 5.2. Here we are
> 
>    LIM(SIN(SIN(z)^2+COS(z)^2),z,inf)
>    Limit[Sin[Sin[z]^2 + Cos[z]^2], z -> Infinity]
>    
>    SIN(1)
>    Sin[1]
> 
>    LIM(SIN(SIN(SIN(SIN(SIN(SIN(z)^2+COS(z)^2))))),z,inf)
>    Limit[Sin[Sin[Sin[Sin[Sin[Sin[z]^2 + Cos[z]^2]]]]], z -> Infinity]
>    
>    SIN(SIN(SIN(SIN(SIN(1)))))
>    Sin[Sin[Sin[Sin[Sin[1]]]]]
>    
>    So why Maxima cannot achieve what other have done OK?
> 
> 
> Sincerely,
> 
> VB
> 
> http://www.cybertester.com/  Cyber Tester, LLC
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> 
> 
> Sunday, August 27, 2006, 5:42:27 PM, you write:
> 
> RF> Yet again you conflate a problem with limit with a 
> simplification problem.
> RF> trigsimp( sin(sin(z)^2+cos(z)^2) );   gives sin(1).
> RF> It is a difficult engineering question to figure out how 
> much work 
> RF> to do on simplifying input without special requests, like 
> trigsimp.  
> RF> If you do too much, commands can take too much time.
> RF> RJF
> 
> 
> >> -----Original Message-----
> >> From: maxima-bounces at math.utexas.edu 
> >> [mailto:maxima-bounces at math.utexas.edu] On Behalf Of Vladimir 
> >> Bondarenko
> >> Sent: Sunday, August 27, 2006 2:02 AM
> >> To: maxima at math.utexas.edu
> >> Subject: Maxima 5.9.3 bug in limit
> >> 
> >> Hello,
> >> 
> >> (%i1) limit(sin(sin(z)^2+cos(z)^2),z,inf);
> >> 
> >> (%o1)                                ind
> >> 
> >> 
> >> Of course, the correct answer is sin(1).
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