- Usage:
`map(M,N,r)`

- Function: map
- Inputs:
`M`, a module`N`, a module, over the same ring`R`as`M`. An integer here stands for the free module of that rank.`r`, a ring element, in the ring`R`

- Optional inputs:
- Degree => ..., -- set the degree of a map
- DegreeLift => ...,
- DegreeMap => ...,

- Outputs:
- a matrix, The map induced by multiplication by
`r`on the generators

- a matrix, The map induced by multiplication by

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 |

If `M` or `N` is not free, then we don't check that the the result is a well defined homomorphism.

- inducedMap -- compute an induced map