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Macaulay2Doc :: sum(ChainComplex)

sum(ChainComplex) -- direct sum of the components of a chain complex

Synopsis

Description

sum C -- yields the sum of the modules in a chain complex.

The degrees of the components are preserved.

i1 : R = ZZ/101[a..d];
i2 : C = res coker vars R

      1      4      6      4      1
o2 = R  <-- R  <-- R  <-- R  <-- R  <-- 0
                                         
     0      1      2      3      4      5

o2 : ChainComplex
i3 : sum C

      16
o3 = R

o3 : R-module, free, degrees {0..1, 3:1, 6:2, 4:3, 4}
i4 : degrees oo

o4 = {{0}, {1}, {1}, {1}, {1}, {2}, {2}, {2}, {2}, {2}, {2}, {3}, {3}, {3},
     ------------------------------------------------------------------------
     {3}, {4}}

o4 : List

See also