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D.15.3.14 chSum
Procedure from library chern.lib (see chern_lib).
- Usage:
- chSum(c, C); c, C lists of polynomials
- Return:
- list of polynomials
- Purpose:
- computes the Chern classes of a direct sum of two vector bundles
- Note:
Example:
| | LIB "chern.lib";
ring r = 0, (c(1..3), C(1..2)), dp;
// Let E be a vector bundle with Chern classes c(1), c(2), c(3).
// Let F be a vector bundle with Chern classes C(1), C(2).
list l=c(1..3);
list L=C(1..2);
// Then the Chern classes of their direct sum are
print( chSum(l, L) );
==> [1]:
==> c(1)+C(1)
==> [2]:
==> c(1)*C(1)+c(2)+C(2)
==> [3]:
==> c(2)*C(1)+c(1)*C(2)+c(3)
==> [4]:
==> c(3)*C(1)+c(2)*C(2)
==> [5]:
==> c(3)*C(2)
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