# Changing MatrixSpace Basis?

```
V = (MatrixSpace(SR, 2, 2))
W = V.subspace_with_basis(
[
matrix([[1,1],[1,1]]),
matrix([[1,0],[pi,1]]),
matrix([[0,7],[8,9]]),
matrix([[1,0],[0,-1]])
]
)
var('a', 'b','c', 'd')
W.coordinate_vector(matrix([[a+b,a+b],[c+d,c+d]]))
```

This doesn't work

The method

`subspace_with_basis`

does not exist for matrix spaces in SageMath 8.7. Which version of SageMath are you using?I am using 8.7. How do I go about doing this then?