##### 7.7.13.0. facWeyl

Procedure from library `ncfactor.lib` (see ncfactor_lib).

Usage:
  facWeyl(h); h a polynomial in the nth Weyl algebra

Return:
  list

Purpose:
  compute all factorizations of a polynomial in the first Weyl algebra

Theory:
  Implements the new algorithm by A. Heinle and V. Levandovskyy, see the thesis of A. Heinle

Assume:
  basering is the nth Weyl algebra, where n in NN.

Note:
  Every entry of the output list is a list with factors for one possible factorization. The first factor is always a constant (1, if no nontrivial constant could be excluded).

Example:

    LIB "ncfactor.lib";
    ring R = 0,(x1,x2,d1,d2),dp;
    matrix C[4][4] = 1,1,1,1,
    1,1,1,1,
    1,1,1,1,
    1,1,1,1;
    matrix D[4][4] = 0,0,1,0,
    0,0,0,1,
    -1,0,0,0,
    0,-1,0,0;
    def r = nc_algebra(C,D);
    setring(r);
    poly h = (d1+1)^2*(d1 + x1*d2);
    facWeyl(h);
    ==> [1]:
    ==>    [1]:
    ==>       1
    ==>    [2]:
    ==>       x1*d1*d2+d1^2+x1*d2+d1+2*d2
    ==>    [3]:
    ==>       d1+1
    ==> [2]:
    ==>    [1]:
    ==>       1
    ==>    [2]:
    ==>       d1+1
    ==>    [3]:
    ==>       d1+1
    ==>    [4]:
    ==>       x1*d2+d1

See also: facFirstShift; facFirstWeyl; facSubWeyl; testNCfac.

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