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 = | 9 2 7 4 2 |
     | 7 8 7 3 4 |
     | 1 8 1 4 0 |

              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,{9, 7, 1}), map(QQ,R,{2, 8, 8}), map(QQ,R,{7, 7, 1}),
     ------------------------------------------------------------------------
     map(QQ,R,{4, 3, 4}), map(QQ,R,{2, 4, 0})}

o3 : List

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

o4 = {7, 7, 1}

o4 : List

i5 : phi#2

o5 = map(QQ,R,{7, 7, 1})

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` :