i1 : m = matrix {{1,2,0,0},{0,0,1,0}}
o1 = | 1 2 0 0 |
| 0 0 1 0 |
2 4
o1 : Matrix ZZ <--- ZZ
|
i2 : compress m
o2 = | 1 2 0 |
| 0 0 1 |
2 3
o2 : Matrix ZZ <--- ZZ
|
The object compress is a method function.