# how to get the transformation matrix for a transformation over 4x4 matrices?

I have the following transformation:

```
M = MatrixSpace(QQ,4,4)
def f(m):
return matrix([
[m[0][0], m[0][1], m[0][2], m[0][3]],
[m[1][3], m[1][0], m[1][1], m[1][2]],
[m[2][2], m[2][3], m[2][0], m[2][1]],
[m[3][1], m[3][2], m[3][3], m[3][0]]
])
print linear_transformation(M, M, f)
```

This is not working - but I can't figure out what linear_transformation is expecting. How can I get this to work? Is this even possible?

The error message

is triggered by

which is quite weird, because

`M`

is indeed a vector space and moreover Sage recognizes it as such:So I would say it is a bug in

`linear_transformation`

...Why not explicitly using vector spaces, as in the doc string of the method? For instance:

(more)