Re: [sage-support] Re: Generating functions slow in Sage?

2014-08-30 Thread Kannappan Sampath
On Fri, Aug 29, 2014 at 2:06 PM, Dima Pasechnik dimp...@gmail.com wrote:

 On 2014-08-29, kcrisman kcris...@gmail.com wrote:
 
 
  Some of you may want to know about this question:
 
 
 http://stackoverflow.com/questions/25570037/best-language-to-do-some-annoying-generating-function-computations
 
  excerpt:
 
  The computation relies on a few ingredients.
 
 1. The first is that I need to be able to compute characters of the
 symmetric group in an efficient manner.


Symmetrica implements the character values using Murnaghan-Nakayama rule
recursively and is very fast.
I think the method is symmetrica.char_values(la, mu)...


 do you mean that the following

 http://www.sagemath.org/doc/reference/combinat/sage/combinat/sf/sf.html#sage.combinat.sf.sf.SymmetricFunctions
 (scroll down to Representation theory of the symmetric group)

 is slow?


 2. The next thing is that I need to arrange these into a generating
 function. This will end up being a generating function in many, many
 variables, although it will be truncated to a finite degree.
 3. Finally, I need to take the formal logarithm (which will be a
 generating function in the same number of variables, of the same
 degree) of
 this and to extract a specific coefficient.
 
  I have coded this before in Maple, but I don't have access to Maple any
  more. I was thinking of doing so in Sage, but step 1 seems not to be well
  implemented (although there is a workaround, but it doesn't seem to be
 very
  efficient). Furthermore, I'm pretty sure that while steps 2 and 3 are
 fine
  in principle, they are very, very slow in Sage.
 

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[sage-support] Re: Generating functions slow in Sage?

2014-08-29 Thread Dima Pasechnik
On 2014-08-29, kcrisman kcris...@gmail.com wrote:


 Some of you may want to know about this question:

 http://stackoverflow.com/questions/25570037/best-language-to-do-some-annoying-generating-function-computations

 excerpt:

 The computation relies on a few ingredients.

1. The first is that I need to be able to compute characters of the 
symmetric group in an efficient manner.

do you mean that the following
http://www.sagemath.org/doc/reference/combinat/sage/combinat/sf/sf.html#sage.combinat.sf.sf.SymmetricFunctions
(scroll down to Representation theory of the symmetric group)

is slow?


2. The next thing is that I need to arrange these into a generating 
function. This will end up being a generating function in many, many 
variables, although it will be truncated to a finite degree.
3. Finally, I need to take the formal logarithm (which will be a 
generating function in the same number of variables, of the same degree) 
 of 
this and to extract a specific coefficient.

 I have coded this before in Maple, but I don't have access to Maple any 
 more. I was thinking of doing so in Sage, but step 1 seems not to be well 
 implemented (although there is a workaround, but it doesn't seem to be very 
 efficient). Furthermore, I'm pretty sure that while steps 2 and 3 are fine 
 in principle, they are very, very slow in Sage.


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