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Re: Any efficient way to make complete homogeneous symmetric functions in Mathematica?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg126829] Re: Any efficient way to make complete homogeneous symmetric functions in Mathematica?
  • From: Bob Hanlon <hanlonr357 at gmail.com>
  • Date: Mon, 11 Jun 2012 00:01:25 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

homogeneousSymmetricPolynomial[k_Integer, var_List] :=
 Module[{n = Length[var], t},
   SeriesCoefficient[Times @@ (1/(1 - var*t)),
    {t, 0, k}]] /;
  0 <= k <= Length[var]

Table[homogeneousSymmetricPolynomial[k, {x1, x2, x3}], {k, 0, 3}]

{1, x1 + x2 + x3, x1^2 + x1*x2 + x2^2 + x1*x3 + x2*x3 +
     x3^2, x1^3 + x1^2*x2 + x1*x2^2 + x2^3 + x1^2*x3 +
     x1*x2*x3 + x2^2*x3 + x1*x3^2 + x2*x3^2 + x3^3}

With[{var = {x1, x2, x3, x4, x5}},
 Module[{m = Length[var]},
  Sum[(-1)^i*SymmetricPolynomial[i, var]*
      homogeneousSymmetricPolynomial[m - i, var],
     {i, 0, m}] == 0 // Simplify]]

True


Bob Hanlon


On Sun, Jun 10, 2012 at 2:14 AM, Rex <aoirex at gmail.com> wrote:
> We do have elementary symmetric functions, SymmetricPolynomial[k,{x_1..x_n}]
> http://reference.wolfram.com/mathematica/ref/SymmetricPolynomial.html
>
> But I didn't found complete homogeneous symmetric functions.
>
> The induction method to compute h_n from e_i and h_j (j<=n-1) is not that efficient.
> https://en.wikipedia.org/wiki/Complete_homogeneous_symmetric_polynomial
>
> Is there any easier way to do this?
>



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