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RationalPoints2 > charpoly

charpoly -- Characteristic and minimal polynomials over the prime field

Synopsis

Description

Obtain the characteristic / minimal polynomial of an element over its prime field.

i1 : QQ[x]; F = splittingField((x^2+1)*(x^2-2));
i3 : minpoly a

      4     2
o3 = x  - 2x  + 9

o3 : QQ[x]
i4 : charpoly(a^2+1, Variable=>y)

      4     3      2
o4 = y  - 8y  + 40y  - 96y + 144

o4 : QQ[y]
i5 : minpoly(a^2+1, Variable=>y)

      2
o5 = y  - 4y + 12

o5 : QQ[y]
i6 : GF 81; minpoly(a+1)

      4    3
o7 = x  + x  - x + 1

     ZZ
o7 : --[x]
      3

The method minpoly can also be used on a field to recover the polynomial used in its definition.

i8 : minpoly F

      4     2
o8 = a  - 2a  + 9

o8 : QQ[a]

Ways to use charpoly :

For the programmer

The object charpoly is a method function with options.