def dmp_pdiv(f, g, u, K):
"""
Polynomial pseudo-division in ``K[X]``.
Examples
========
>>> from diofant.polys import ring, ZZ
>>> R, x,y = ring("x,y", ZZ)
>>> R.dmp_pdiv(x**2 + x*y, 2*x + 2)
(2*x + 2*y - 2, -4*y + 4)
"""
if not u:
return dup_pdiv(f, g, K)
df = dmp_degree(f, u)
dg = dmp_degree(g, u)
if dg < 0:
raise ZeroDivisionError("polynomial division")
q, r, dr = dmp_zero(u), f, df
if df < dg:
return q, r
N = df - dg + 1
lc_g = dmp_LC(g, K)
while True:
lc_r = dmp_LC(r, K)
j, N = dr - dg, N - 1
Q = dmp_mul_term(q, lc_g, 0, u, K)
q = dmp_add_term(Q, lc_r, j, u, K)
R = dmp_mul_term(r, lc_g, 0, u, K)
G = dmp_mul_term(g, lc_r, j, u, K)
r = dmp_sub(R, G, u, K)
_dr, dr = dr, dmp_degree(r, u)
if dr < dg:
break
elif not (dr < _dr):
raise PolynomialDivisionFailed(f, g, K)
c = dmp_pow(lc_g, N, u - 1, K)
q = dmp_mul_term(q, c, 0, u, K)
r = dmp_mul_term(r, c, 0, u, K)
return q, r
def test_printing():
f, g = [dmp_normal([], 0, EX)] * 2
e = PolynomialDivisionFailed(f, g, EX)
assert str(e)[:57] == ("couldn't reduce degree in a polynomial "
"division algorithm")
assert str(e)[-140:][:57] == ("You may want to use a different "
"simplification algorithm.")
f, g = [dmp_normal([], 0, RR)] * 2
e = PolynomialDivisionFailed(f, g, RR)
assert str(e)[-139:][:74] == ("Your working precision or tolerance of "
"computations may be set improperly.")
f, g = [dmp_normal([], 0, ZZ)] * 2
e = PolynomialDivisionFailed(f, g, ZZ)
assert str(e)[-168:][:80] == (
"Zero detection is guaranteed in this "
"coefficient domain. This may indicate a bug")
e = OperationNotSupported(Poly(x), 'spam')
assert str(e).find('spam') >= 0
assert str(e).find('operation not supported') >= 0
exc = PolificationFailed(1, x, x**2)
assert str(exc).find("can't construct a polynomial from x") >= 0
exc = PolificationFailed(1, [x], [x**2], True)
assert str(exc).find("can't construct polynomials from x") >= 0
e = ComputationFailed('LT', 1, exc)
assert str(e).find('failed without generators') >= 0
assert str(e).find('x**2') >= 0
e = ExactQuotientFailed(Poly(x), Poly(x**2))
assert str(e).find('does not divide') >= 0
assert str(e).find('x**2') >= 0
assert str(e).find('in ZZ') < 0
e = ExactQuotientFailed(Poly(x), Poly(x**2), ZZ)
assert str(e).find('in ZZ') >= 0
def dup_pdiv(f, g, K):
"""
Polynomial pseudo-division in ``K[x]``.
Examples
========
>>> from diofant.polys import ring, ZZ
>>> R, x = ring("x", ZZ)
>>> R.dup_pdiv(x**2 + 1, 2*x - 4)
(2*x + 4, 20)
"""
df = dup_degree(f)
dg = dup_degree(g)
q, r, dr = [], f, df
if not g:
raise ZeroDivisionError("polynomial division")
elif df < dg:
return q, r
N = df - dg + 1
lc_g = dup_LC(g, K)
while True:
lc_r = dup_LC(r, K)
j, N = dr - dg, N - 1
Q = dup_mul_ground(q, lc_g, K)
q = dup_add_term(Q, lc_r, j, K)
R = dup_mul_ground(r, lc_g, K)
G = dup_mul_term(g, lc_r, j, K)
r = dup_sub(R, G, K)
_dr, dr = dr, dup_degree(r)
if dr < dg:
break
elif not (dr < _dr):
raise PolynomialDivisionFailed(f, g, K)
c = lc_g**N
q = dup_mul_ground(q, c, K)
r = dup_mul_ground(r, c, K)
return q, r
def dmp_ff_div(f, g, u, K):
"""
Polynomial division with remainder over a field.
Examples
========
>>> from diofant.polys import ring, QQ
>>> R, x,y = ring("x,y", QQ)
>>> R.dmp_ff_div(x**2 + x*y, 2*x + 2)
(1/2*x + 1/2*y - 1/2, -y + 1)
"""
if not u:
return dup_ff_div(f, g, K)
df = dmp_degree(f, u)
dg = dmp_degree(g, u)
if dg < 0:
raise ZeroDivisionError("polynomial division")
q, r, dr = dmp_zero(u), f, df
if df < dg:
return q, r
lc_g, v = dmp_LC(g, K), u - 1
while True:
lc_r = dmp_LC(r, K)
c, R = dmp_ff_div(lc_r, lc_g, v, K)
if not dmp_zero_p(R, v):
break
j = dr - dg
q = dmp_add_term(q, c, j, u, K)
h = dmp_mul_term(g, c, j, u, K)
r = dmp_sub(r, h, u, K)
_dr, dr = dr, dmp_degree(r, u)
if dr < dg:
break
elif not (dr < _dr):
raise PolynomialDivisionFailed(f, g, K)
return q, r
def dup_rr_div(f, g, K):
"""
Univariate division with remainder over a ring.
Examples
========
>>> from diofant.polys import ring, ZZ
>>> R, x = ring("x", ZZ)
>>> R.dup_rr_div(x**2 + 1, 2*x - 4)
(0, x**2 + 1)
"""
df = dup_degree(f)
dg = dup_degree(g)
q, r, dr = [], f, df
if not g:
raise ZeroDivisionError("polynomial division")
elif df < dg:
return q, r
lc_g = dup_LC(g, K)
while True:
lc_r = dup_LC(r, K)
if lc_r % lc_g:
break
c = K.exquo(lc_r, lc_g)
j = dr - dg
q = dup_add_term(q, c, j, K)
h = dup_mul_term(g, c, j, K)
r = dup_sub(r, h, K)
_dr, dr = dr, dup_degree(r)
if dr < dg:
break
elif not (dr < _dr):
raise PolynomialDivisionFailed(f, g, K)
return q, r
def dup_prem(f, g, K):
"""
Polynomial pseudo-remainder in ``K[x]``.
Examples
========
>>> from diofant.polys import ring, ZZ
>>> R, x = ring("x", ZZ)
>>> R.dup_prem(x**2 + 1, 2*x - 4)
20
"""
df = dup_degree(f)
dg = dup_degree(g)
r, dr = f, df
if not g:
raise ZeroDivisionError("polynomial division")
elif df < dg:
return r
N = df - dg + 1
lc_g = dup_LC(g, K)
while True:
lc_r = dup_LC(r, K)
j, N = dr - dg, N - 1
R = dup_mul_ground(r, lc_g, K)
G = dup_mul_term(g, lc_r, j, K)
r = dup_sub(R, G, K)
_dr, dr = dr, dup_degree(r)
if dr < dg:
break
elif not (dr < _dr):
raise PolynomialDivisionFailed(f, g, K)
return dup_mul_ground(r, lc_g**N, K)