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D.5.4.19 pdivisorplus
Procedure from library divisors.lib (see divisors_lib).
- Usage:
- pdivisorplus(A ,B); A + B; A = pdivisor, B = pdivisor.
- Assume:
- A and B are polyhedral divisors on X.
- Return:
- a pdivisor on X
- Theory:
- The procedure will add the polyhedral formal sums by doing Minkowski sums.
Example:
| | LIB "divisors.lib";
==> Welcome to polymake version
==> Copyright (c) 1997-2015
==> Ewgenij Gawrilow, Michael Joswig (TU Darmstadt)
==> http://www.polymake.org
LIB("polymake.so");
ring r=31991,(x,y,z),dp;
ideal I = y^2*z - x*(x-z)*(x+3*z);
qring Q = std(I);
divisor A = makeDivisor(ideal(x,z),ideal(1));
divisor B = makeDivisor(ideal(x,y),ideal(1));
intmat M[4][4]= 1,4,0,0,
1,0,3,0,
0,0,0,2,
1,1,1,1;
polytope PP = polytopeViaPoints(M);
pdivisor pD = makePDivisor(list(list(PP,A),list(PP,B)));
pdivisorplus(pD,pD);
==> polymake: used package ppl
==> The Parma Polyhedra Library (PPL): A C++ library for convex polyhedra
==> and other numerical abstractions.
==> http://www.cs.unipr.it/ppl/
==>
==> tail=<cone>
==> summands=<list>
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