Ring _ ZZ -- get a variable by number

Ring _ ZZ -- get a variable by number

Synopsis:

Operator: _

Input:

an instance of class Ring.

an instance of class ZZ.

Output:

an instance of class RingElement.

R_i -- produce the i-th generator of a ring R.

The indexing of generators is based on 0, so R_0 would be the first one, and so on.

i1 : R = ZZ[a..d]



o1 = R



o1 : PolynomialRing

i2 : R_2



o2 = c



o2 : R

Code:

     -- ../m2/enginering.m2:213-217
     Ring _ ZZ := RingElement => (R,i) -> (
          if R.?generators 
          then R.generators#i
          else error "ring has no generators"
          )