1 | initial version |

You are absolutely right, while being correct on positive integers, the expression is not correct when specialized to `k=0`

:

```
sage: [B.subs(k=i) == A^i for i in range(20)]
[False,
True,
True,
True,
True,
True,
True,
True,
True,
True,
True,
True,
True,
True,
True,
True,
True,
True,
True,
True]
sage: B.subs(k=0)
[ -1 -4 -8]
[1/2 2 2]
[ 0 0 1]
```

Thanks for reporting, it is now trac ticket 25520

Copyright Sage, 2010. Some rights reserved under creative commons license. Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.