source(RingMap) -- find the source ring for a map of rings

Synopsis

• Function: source

• Usage:

  source f

• Inputs:
  • f, a ring map
• Outputs:
  • the source ring of the map

Description

i1 : S = ZZ/10007[x, y, z];

i2 : R = ZZ/10007[t];

i3 : f = map(R,S,{t^3,t^4,t^5})

                  3   4   5
o3 = map (R, S, {t , t , t })

o3 : RingMap R <-- S

i4 : source f

o4 = S

o4 : PolynomialRing