Hello,
My new(er) Permutations combinatorial class should handle things correctly.
sage: MS = MatrixSpace(QQ, 2, 2)
sage: A = MS([1,2,3,4])
sage: Permutations(A.rows()).list()
[[(1, 2), (3, 4)], [(3, 4), (1, 2)]]
sage: MS = MatrixSpace(GF(2),2,2)
sage: A = MS([1,2,3,4])
sage: Permutations(A.rows()).list()
[[(1, 0), (1, 0)]]
--Mike
On 10/27/07, David Joyner <[EMAIL PROTECTED]> wrote:
>
> Hi:
> Either a bug in combinat.py's permutations, or an indication that
> it needs to be rewritten. (permutations is a GAP wrapper which
> I might have written, so should probably fix ...)
>
> - David Joyner
>
>
> sage: MS = MatrixSpace(QQ,2,2)
> sage: A = MS([1,2,3,4])
> sage: permutations(A.rows())
> [[(3, 4), (1, 2)], [(1, 2), (3, 4)]]
> sage:
> sage: MS = MatrixSpace(GF(2),2,2)
> sage: A = MS([1,2,3,4])
> sage: permutations(A.rows())
> ---------------------------------------------------------------------------
> <type 'exceptions.RuntimeError'> Traceback (most recent call last)
>
> /Users/wdj/sagefiles/sage-2.8.2/<ipython console> in <module>()
>
> /Users/wdj/sagefiles/sage-2.8.2/local/lib/python2.5/site-packages/sage/combinat/combinat.py
> in permutations(mset)
> 1552
> 1553 """
> -> 1554 ans=gap.eval("PermutationsList(%s)"%mset)
> 1555 return eval(ans)
> 1556
>
> /Users/wdj/sagefiles/sage-2.8.2/local/lib/python2.5/site-packages/sage/interfaces/gap.py
> in eval(self, x, newlines, strip)
> 301 if len(x) == 0 or x[len(x) - 1] != ';':
> 302 x += ';'
> --> 303 s = Expect.eval(self, x)
> 304 if newlines:
> 305 return s
>
> /Users/wdj/sagefiles/sage-2.8.2/local/lib/python2.5/site-packages/sage/interfaces/expect.py
> in eval(self, code, strip, **kwds)
> 648 code = code.strip()
> 649 try:
> --> 650 return '\n'.join([self._eval_line(L, **kwds) for L
> in code.split('\n') if L != ''])
> 651 except KeyboardInterrupt:
> 652 # DO NOT CATCH KeyboardInterrupt, as it is being caught
>
> /Users/wdj/sagefiles/sage-2.8.2/local/lib/python2.5/site-packages/sage/interfaces/gap.py
> in _eval_line(self, line, allow_use_file, wait_for_prompt)
> 502 return ''
> 503 else:
> --> 504 raise RuntimeError, message
> 505
> 506 except KeyboardInterrupt:
>
> <type 'exceptions.RuntimeError'>: Gap produced error output
> Permutation: <expr> must be a positive integer (not a integer)
>
> executing PermutationsList([(1, 0), (1, 0)]);
>
> >
>
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