If
r is not zero, then either
M and
N should be equal, or they should have the same number of generators. This gives the same map as r * map(M,N,1). map(M,N,1) is the map induced by the identity on the generators of M and N.
i1 : R = QQ[x];
|
i2 : map(R^2,R^3,0)
o2 = 0
2 3
o2 : Matrix R <--- R
|
i3 : f = map(R^2,R^2,x)
o3 = | x 0 |
| 0 x |
2 2
o3 : Matrix R <--- R
|
i4 : f == x *map(R^2,R^2,1)
o4 = true
|