ChainComplex ++ ChainComplex -- direct sum

ChainComplex ++ ChainComplex -- direct sum

C++D -- direct sum of chain complexes.

i1 : C = resolution cokernel matrix {{4,5}}



       1       2       1

o1 = ZZ  <-- ZZ  <-- ZZ

                     

     0       1       2



o1 : ChainComplex

i2 : C ++ C[-2]



       1       2       2       2       1

o2 = ZZ  <-- ZZ  <-- ZZ  <-- ZZ  <-- ZZ

                                     

     0       1       2       3       4



o2 : ChainComplex

Synopsis of use:

Operator: ++

Class of argument 1: ChainComplex

Class of argument 2: ChainComplex

Class of typical returned value: ChainComplex

Next more general method: GradedModule ++ GradedModule -- a binary operator, usually used for direct sum

Code:

     -- ../m2/chaincomplexes.m2:502
     ChainComplex ++ ChainComplex := ChainComplex => (C,D) -> directSum(C,D)