Let
f1,...,fn be a polynomials two groups of variables
X1,...,Xn and
a1,...,as and such that
f1,...,fn are homogeneous polynomials with respect to the variables
X1,...,Xn. This function returns two matrices
M1 and
M2 such that
det(D1)/det(D2) is the Macaulay resultant of
f1,...,fn providing det(D
2) is nonzero.
Remark: if D2 is the empty matrix, its determinant has to be understood as 1 (and not zero, which is the case in Macaulay2 since the empty matrix is identified to the zero.
i1 : R=QQ[a..i,x,y,z]
o1 = R
o1 : PolynomialRing
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i2 : f1 = a*x+b*y+c*z
o2 = a*x + b*y + c*z
o2 : R
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i3 : f2 = d*x+e*y+f*z
o3 = d*x + e*y + f*z
o3 : R
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i4 : f3 = g*x+h*y+i*z
o4 = g*x + h*y + i*z
o4 : R
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i5 : M = matrix{{f1,f2,f3}}
o5 = | ax+by+cz dx+ey+fz gx+hy+iz |
1 3
o5 : Matrix R <--- R
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i6 : l = {x,y,z}
o6 = {x, y, z}
o6 : List
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i7 : MR = macaulayFormula (l,M)
o7 = ({1} | a d g |, 0)
{1} | b e h |
{1} | c f i |
o7 : Sequence
|