makeRingMaps -- evaluation on points

Synopsis

Usage:
makeRingMaps(M,R)
Inputs:
- M, a matrix, in which each column consists of the coordinates of a point
- R, a polynomial ring, coordinate ring of the affine space containing the points
Outputs:
- a list, of ring maps corresponding to evaluations at each point

Description

Giving the coordinates of a point in affine space is equivalent to giving a ring map from the polynomial ring to the ground field: evaluation at the point. Given a finite collection of points encoded as the columns of a matrix, this function returns a corresponding list of ring maps.

i1 : M = random(ZZ^3, ZZ^5)

o1 = | 6 1 8 0 0 |
     | 2 0 8 7 8 |
     | 7 7 7 1 9 |

              3        5
o1 : Matrix ZZ  <--- ZZ

i2 : R = QQ[x,y,z]

o2 = R

o2 : PolynomialRing

i3 : phi = makeRingMaps(M,R)

o3 = {map(QQ,R,{6, 2, 7}), map(QQ,R,{1, 0, 7}), map(QQ,R,{8, 8, 7}),
     ------------------------------------------------------------------------
     map(QQ,R,{0, 7, 1}), map(QQ,R,{0, 8, 9})}

o3 : List

i4 : apply (gens(R),r->phi#2 r)

o4 = {8, 8, 7}

o4 : List

i5 : phi#2

o5 = map(QQ,R,{8, 8, 7})

o5 : RingMap QQ <--- R

Ways to use `makeRingMaps` :

makeRingMaps(Matrix,Ring)

makeRingMaps -- evaluation on points

Synopsis

Description

Ways to use makeRingMaps :

Ways to use `makeRingMaps` :