# Ring _ ZZ -- get a ring variable by index

## Synopsis

• Operator: _
• Usage:
R_i
• Inputs:
• Outputs:
• , the i-th generator of the ring R

## Description

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

If the coefficient ring is a polynomial ring, then the numbering matches that in the list returned by generators.

 i3 : S = R[x,y,z] o3 = S o3 : PolynomialRing i4 : generators(S,CoefficientRing=>ZZ) o4 = {x, y, z, a, b, c, d} o4 : List i5 : S_2 o5 = z o5 : S i6 : S_6 o6 = d o6 : S