Description
The first variable in a polynomial ring has index 0, the second has index 1, etc. This function returns a list (in ascending order) of the indices of all of the variables that occur in
f.
i1 : R = QQ[a..g]
o1 = R
o1 : PolynomialRing
|
i2 : F = a^3+b^2*c+3*f^10*d-1+e-e
10 3 2
o2 = 3d*f + a + b c - 1
o2 : R
|
i3 : indices F
o3 = {0, 1, 2, 3, 5}
o3 : List
|
i4 : index a
o4 = 0
|
i5 : support F
o5 = {a, b, c, d, f}
o5 : List
|
The same works for matrices.
i6 : M = matrix"a+b,c+e;2a-e,3b-c4"
o6 = | a+b c+e |
| 2a-e -c4+3b |
2 2
o6 : Matrix R <-- R
|
i7 : indices M
o7 = {0, 1, 2, 4}
o7 : List
|
i8 : support M
o8 = {a, b, c, e}
o8 : List
|
This use of
indices has no relationship with the use for specifying parts of a direct sum