Description
Works for modules, chain complexes, etc. The components of the sum can be recovered with
components.
i1 : isDirectSum ZZ^6
o1 = false
|
i2 : F = ZZ^2 ++ ZZ^3
5
o2 = ZZ
o2 : ZZ-module, free
|
i3 : isDirectSum F
o3 = true
|
i4 : components F
2 3
o4 = {ZZ , ZZ }
o4 : List
|