RelativeCanonicalDivisor -- computes the relative canonical divisor

Synopsis

Usage:

RelativeCanonicalDivisor(E)
Inputs:
- E, Intersection matrix.
Outputs:
- The relative canonical divisor of the resolution.

Description

Starting form the intersection matrix as presented in [AAD14], it returns the relative canonical divisor of the resolution as a matrix 1 x m.

i1 : E = matrix({{ -5,  0,  1,  0,  1},
                     {  0, -2,  1,  0,  0},
                     {  1,  1, -1,  0,  0},
                     {  0,  0,  0, -2,  1},
                     {  1,  0,  0,  1, -1}})

o1 = | -5 0  1  0  1  |
     | 0  -2 1  0  0  |
     | 1  1  -1 0  0  |
     | 0  0  0  -2 1  |
     | 1  0  0  1  -1 |

              5       5
o1 : Matrix ZZ  <-- ZZ

i2 : RelativeCanonicalDivisor(E)

o2 = | 1 2 4 2 4 |

              1       5
o2 : Matrix QQ  <-- QQ

For the programmer

The object RelativeCanonicalDivisor is a function closure.