MathGroup Archive 1996

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

Search the Archive

Integral over Spher. Harmon.


to those having Mma 3.0 :
how does 
Integrate[SphericalHarmonicY[l,m,th,fi]Sin[th],{th,0,Pi},{fi,0,2Pi}]
evaluate for unspecified l and m ?
does it bounce back the input, like in version 2.3.3 ?
or does it give the proper :
If[l==0&&m==0, 2 Sqrt[Pi], 0]?
Check that, in version 2.3.3 , even explicitely limiting l and m to integers :

Integrate[SphericalHarmonicY[l_Integer,m_Integer,th,fi]Sin[th],{th,0,Pi},{fi
,0,2Pi}]
does not produce those results.

Neither does :
Integrate[SphericalHarmonicY[l_/;IntegerQ[l],m_/;IntegerQ[m],th,fi]Sin[th],{
th,0,Pi},{fi,0,2Pi}]

Alternative question : is it easier in Mma 3.0 to "lock" a variable to
integer, positive, real, etc.. domains ? In other words, does Sin[2
n_Integer Pi] evaluate to zero ?
In previous questions & answer sessions (here and elsewhere), it was said
that "locking" variables in such way is dangerous, undesirable , and leads
to errors.
Possible, but function definitions and variable assignments using "Set" are
just as dangerous. Since they show up nicely using "?symbol", I see no
danger. It feels as though a means of user control is withheld by not
allowing "locking".

How does Mma 3.0 react in this respect ?

Wouter.



==== [MESSAGE SEPARATOR] ====


  • Prev by Date: Re: help!! Plot3D of ellipsoid
  • Next by Date: Re: Re: Mathematica and PPP
  • Previous by thread: Re:programming competition Correction
  • Next by thread: Modular Multiplication Algorithms