Python Poly.coeff方法代码示例

# 需要导入模块: from sympy import Poly [as 别名]
# 或者: from sympy.Poly import coeff [as 别名]
def test_coeff():
    p = Poly(3*x**2*y + 4*x*y**2 + 1, x, y)

    assert p.coeff(0, 0) == p.coeff() == 1

    assert p.coeff(2, 1) == 3
    assert p.coeff(1, 2) == 4
    assert p.coeff(1, 1) == 0

# 需要导入模块: from sympy import Poly [as 别名]
# 或者: from sympy.Poly import coeff [as 别名]
def poly_factorize(poly):
    """Factorize multivariate polynomials into a sum of products of monomials.

    This function can be used to decompose polynomials into a form which
    minimizes the number of additions and multiplications, and which thus
    can be evaluated efficently."""
    max_deg = {}

    if 'horner' in dir(sympy):
        return sympy.horner(poly)

    if not isinstance(poly, Poly):
        poly = Poly(sympy.expand(poly), *poly.atoms(Symbol))

    denom, poly = poly.as_integer()

    # Determine the order of factorization.  We proceed through the
    # symbols, starting with the one present in the highest order
    # in the polynomial.
    for i, sym in enumerate(poly.symbols):
        max_deg[i] = 0

    for monom in poly.monoms:
        for i, symvar in enumerate(monom):
            max_deg[i] = max(max_deg[i], symvar)

    ret_poly = 0
    monoms = list(poly.monoms)

    for isym, maxdeg in sorted(max_deg.items(), key=itemgetter(1), reverse=True):
        drop_idx = []
        new_poly = []

        for i, monom in enumerate(monoms):
            if monom[isym] > 0:
                drop_idx.append(i)
                new_poly.append((poly.coeff(*monom), monom))

        if not new_poly:
            continue

        ret_poly += sympy.factor(Poly(new_poly, *poly.symbols))

        for idx in reversed(drop_idx):
            del monoms[idx]

    # Add any remaining O(1) terms.
    new_poly = []
    for i, monom in enumerate(monoms):
        new_poly.append((poly.coeff(*monom), monom))

    if new_poly:
        ret_poly += Poly(new_poly, *poly.symbols)

    return ret_poly / denom

# 需要导入模块: from sympy import Poly [as 别名]
# 或者: from sympy.Poly import coeff [as 别名]
def main():
    x=Symbol("x")
    s = Poly(A(x), x)
    num = [s.coeff(n) for n in range(11)]

    print s.as_basic()
    print num