Dear List,
I'm trying to substitute various expressions for the variables of
symmetric polynomials returned by
SymmetricFunctionAlgebra_generic(...).expand() but I can't figure out
how to ask Sage to replace these variables or coerce them to some
other polynomial ring. E.g.:
----------------------------------------------------------------------
| Sage Version 4.1.2, Release Date: 2009-10-14 |
| Type notebook() for the GUI, and license() for information. |
----------------------------------------------------------------------
sage: R.<x0,x1,x2> = QQ['x0','x1','x2']
sage: x3=-(x0+x1+x2)
sage: e = SFAElementary(QQ)
sage: e([1]).expand(4)
x0 + x1 + x2 + x3
sage: e([1]).expand(4,alphabet=[x0,x1,x2,x3])
<snip long error trace>
ValueError: variable names must be alphanumeric, but one is '-x0 - x1 - x2'
which is not.
sage: e([1]).expand(4).subs([x0,x1,x2,x3])
<snip another long error trace>
AttributeError: 'list' object has no attribute 'iteritems'
sage: e([1]).expand(4).subs({x0:x0,x1:x1,x2:x2,x3:x3,x4:x4})
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
/usr/src/local/sage-4.1.2/<ipython console> in <module>()
NameError: name 'x4' is not defined
sage: R(e([1]).expand(4))
<snip huge error trace>
TypeError: not a constant polynomial
I think it should be quite obvious what I'm trying to do there (the
result should be 0, of course). How can I make it work?
Evidently e([1]).expand(4) returns a polynomial constructed of
variables x0,x1,x2,x3 which are not my x0,x1,x2 and x3. How can I
force it to use my variables x0,x1,x2,x3?
And, more generally, given a list of elements in a ring, how can I
efficiently (in terms of number of keystrokes!) compute the
elementary symmetric functions of these elements?
Thanks in advance,
--
David A. Madore
( http://www.madore.org/~david/ )
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to sage-support@googlegroups.com
To unsubscribe from this group, send email to
sage-support-unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/sage-support
URL: http://www.sagemath.org
-~----------~----~----~----~------~----~------~--~---
