scale -- reduces a list or divisor by the gcd of its coefficients

Synopsis

Usage:

scale(D)
Inputs:
- D, an instance of the type SymmetricDivisorM0nbar,
Outputs:
- E, an instance of the type SymmetricDivisorM0nbar,

Description

Let $D$ be an $S_n$ symmetric $Q$-divisor on $\bar{M}_{0,n}$. This function reduces a symmetric divisor $D$ by the gcd of its coefficients in the standard basis. This gives a canonical representative of each nonzero ray in $Pic(\bar{M}_{0,n})_Q^{S_n}$.

i1 : D=symmetricDivisorM0nbar(6,288*B_2+144*B_3)

o1 = 288*B  + 144*B
          2        3

o1 : S_6-symmetric divisor on M-0-6-bar

i2 : scale(D)

o2 = 2*B  + B
        2    3

o2 : S_6-symmetric divisor on M-0-6-bar

Ways to use scale :

scale(SymmetricDivisorM0nbar)

For the programmer

The object scale is a method function.