minors(ZZ,Matrix) -- ideal generated by minors

Synopsis

• Function: minors
• Usage:
minors(n,M)
• Inputs:
• n, an integer, order of the minor
• M, , a map between free modules
• Optional inputs:
• First => a list, default value null, if given, should be a list of two integer lists, which will be the first minor computed
• Limit => an integer, default value infinity, the maximum number of minors to find
• Strategy => ..., default value null, choose between Bareiss, Cofactor and Dynamic algorithms
• Outputs:
• an ideal, the ideal generated by the n by n minors of the matrix M

Description

Minors are generated in the same order as that used by subsets(ZZ,ZZ).
 i1 : R = ZZ[a..f]; i2 : M = matrix{{a,b,c},{d,e,f}} o2 = | a b c | | d e f | 2 3 o2 : Matrix R <--- R i3 : minors(2,M) o3 = ideal (- b*d + a*e, - c*d + a*f, - c*e + b*f) o3 : Ideal of R i4 : minors(2,M,Limit=>1) o4 = ideal(- b*d + a*e) o4 : Ideal of R

When n is negative, the unit ideal is returned, to preserve the expected ordering among the resulting ideals.

 i5 : minors(1,M) o5 = ideal (a, d, b, e, c, f) o5 : Ideal of R i6 : minors(0,M) o6 = ideal 1 o6 : Ideal of R i7 : minors(-1,M) o7 = ideal 1 o7 : Ideal of R