Computing Polynomial Resultants: Bezout's Determinant
vs. Collins' Reduced P.R.S. Algorithm
Algorithms for computing the resultant of two
polynomials in several variables, a key repetitive 
step of computation in solving systems of polynomial
equations by elimination, are studied.  Determining 
the best algorithm for computer implementation depends
upon the extent to which extraneous factors are 
introduced, the extent of propagation of errors caused by
truncation of real coefficients, memory requirements, 
and computing speed.  Preliminary considerations narrow
the choice of the best algorithm to Bezout's 
determinant and Collins' reduced polynomial remainder sequence
(p.r.s.) algorithm.  Detailed tests performed 
on sample problems conclusively show that Bezout's determinant
is superior in all respects except for 
univariate polynomials, in which case Collins' reduced
p.r.s. algorithm is somewhat faster.  In particular 
Bezout's determinant proves to be strikingly superior in
numerical accuracy, displaying excellent stability 
with regard to round-off errors. Results of tests are reported in detail.
CACM January, 1969
Ku, S. Y.
Adler, R. J.
