def _minpoly_compose(ex, x, dom):
"""
Computes the minimal polynomial of an algebraic element
using operations on minimal polynomials
Examples
========
>>> from sympy import minimal_polynomial, sqrt, Rational
>>> from sympy.abc import x, y
>>> minimal_polynomial(sqrt(2) + 3*Rational(1, 3), x, compose=True)
x**2 - 2*x - 1
>>> minimal_polynomial(sqrt(y) + 1/y, x, compose=True)
x**2*y**2 - 2*x*y - y**3 + 1
"""
if ex.is_Rational:
return ex.q*x - ex.p
if ex is I:
return x**2 + 1
if hasattr(dom, 'symbols') and ex in dom.symbols:
return x - ex
if dom.is_QQ and _is_sum_surds(ex):
# eliminate the square roots
ex -= x
while 1:
ex1 = _separate_sq(ex)
if ex1 is ex:
return ex
else:
ex = ex1
if ex.is_Add:
res = _minpoly_add(x, dom, *ex.args)
elif ex.is_Mul:
f = Factors(ex).factors
r = sift(f.items(), lambda itx: itx[0].is_rational and itx[1].is_rational)
if r[True] and dom == QQ:
ex1 = Mul(*[bx**ex for bx, ex in r[False] + r[None]])
r1 = r[True]
dens = [y.q for _, y in r1]
lcmdens = reduce(lcm, dens, 1)
nums = [base**(y.p*lcmdens // y.q) for base, y in r1]
ex2 = Mul(*nums)
mp1 = minimal_polynomial(ex1, x)
# use the fact that in SymPy canonicalization products of integers
# raised to rational powers are organized in relatively prime
# bases, and that in ``base**(n/d)`` a perfect power is
# simplified with the root
mp2 = ex2.q*x**lcmdens - ex2.p
ex2 = ex2**Rational(1, lcmdens)
res = _minpoly_op_algebraic_element(Mul, ex1, ex2, x, dom, mp1=mp1, mp2=mp2)
else:
res = _minpoly_mul(x, dom, *ex.args)
elif ex.is_Pow:
res = _minpoly_pow(ex.base, ex.exp, x, dom)
elif ex.__class__ is C.sin:
res = _minpoly_sin(ex, x)
elif ex.__class__ is C.cos:
res = _minpoly_cos(ex, x)
elif ex.__class__ is C.exp:
res = _minpoly_exp(ex, x)
elif ex.__class__ is RootOf:
res = _minpoly_rootof(ex, x)
else:
raise NotAlgebraic("%s doesn't seem to be an algebraic element" % ex)
return res
def _minpoly_compose(ex, x, dom):
"""
Computes the minimal polynomial of an algebraic element
using operations on minimal polynomials
Examples
========
>>> from sympy import minimal_polynomial, sqrt, Rational
>>> from sympy.abc import x, y
>>> minimal_polynomial(sqrt(2) + 3*Rational(1, 3), x, compose=True)
x**2 - 2*x - 1
>>> minimal_polynomial(sqrt(y) + 1/y, x, compose=True)
x**2*y**2 - 2*x*y - y**3 + 1
"""
if ex.is_Rational:
return ex.q * x - ex.p
if ex is I:
_, factors = factor_list(x**2 + 1, x, domain=dom)
return x**2 + 1 if len(factors) == 1 else x - I
if ex is S.GoldenRatio:
_, factors = factor_list(x**2 - x - 1, x, domain=dom)
if len(factors) == 1:
return x**2 - x - 1
else:
return _choose_factor(factors, x, (1 + sqrt(5)) / 2, dom=dom)
if ex is S.TribonacciConstant:
_, factors = factor_list(x**3 - x**2 - x - 1, x, domain=dom)
if len(factors) == 1:
return x**3 - x**2 - x - 1
else:
fac = (1 + cbrt(19 - 3 * sqrt(33)) + cbrt(19 + 3 * sqrt(33))) / 3
return _choose_factor(factors, x, fac, dom=dom)
if hasattr(dom, 'symbols') and ex in dom.symbols:
return x - ex
if dom.is_QQ and _is_sum_surds(ex):
# eliminate the square roots
ex -= x
while 1:
ex1 = _separate_sq(ex)
if ex1 is ex:
return ex
else:
ex = ex1
if ex.is_Add:
res = _minpoly_add(x, dom, *ex.args)
elif ex.is_Mul:
f = Factors(ex).factors
r = sift(f.items(),
lambda itx: itx[0].is_Rational and itx[1].is_Rational)
if r[True] and dom == QQ:
ex1 = Mul(*[bx**ex for bx, ex in r[False] + r[None]])
r1 = dict(r[True])
dens = [y.q for y in r1.values()]
lcmdens = reduce(lcm, dens, 1)
neg1 = S.NegativeOne
expn1 = r1.pop(neg1, S.Zero)
nums = [base**(y.p * lcmdens // y.q) for base, y in r1.items()]
ex2 = Mul(*nums)
mp1 = minimal_polynomial(ex1, x)
# use the fact that in SymPy canonicalization products of integers
# raised to rational powers are organized in relatively prime
# bases, and that in ``base**(n/d)`` a perfect power is
# simplified with the root
# Powers of -1 have to be treated separately to preserve sign.
mp2 = ex2.q * x**lcmdens - ex2.p * neg1**(expn1 * lcmdens)
ex2 = neg1**expn1 * ex2**Rational(1, lcmdens)
res = _minpoly_op_algebraic_element(Mul,
ex1,
ex2,
x,
dom,
mp1=mp1,
mp2=mp2)
else:
res = _minpoly_mul(x, dom, *ex.args)
elif ex.is_Pow:
res = _minpoly_pow(ex.base, ex.exp, x, dom)
elif ex.__class__ is sin:
res = _minpoly_sin(ex, x)
elif ex.__class__ is cos:
res = _minpoly_cos(ex, x)
elif ex.__class__ is tan:
res = _minpoly_tan(ex, x)
elif ex.__class__ is exp:
res = _minpoly_exp(ex, x)
elif ex.__class__ is CRootOf:
res = _minpoly_rootof(ex, x)
else:
raise NotAlgebraic("%s does not seem to be an algebraic element" % ex)
return res
def _minpoly_compose(ex, x, dom):
"""
Computes the minimal polynomial of an algebraic element
using operations on minimal polynomials
Examples
========
>>> from sympy import minimal_polynomial, sqrt, Rational
>>> from sympy.abc import x, y
>>> minimal_polynomial(sqrt(2) + 3*Rational(1, 3), x, compose=True)
x**2 - 2*x - 1
>>> minimal_polynomial(sqrt(y) + 1/y, x, compose=True)
x**2*y**2 - 2*x*y - y**3 + 1
"""
if ex.is_Rational:
return ex.q * x - ex.p
if ex is I:
return x**2 + 1
if hasattr(dom, 'symbols') and ex in dom.symbols:
return x - ex
if dom.is_QQ and _is_sum_surds(ex):
# eliminate the square roots
ex -= x
while 1:
ex1 = _separate_sq(ex)
if ex1 is ex:
return ex
else:
ex = ex1
if ex.is_Add:
res = _minpoly_add(x, dom, *ex.args)
elif ex.is_Mul:
f = Factors(ex).factors
r = sift(f.items(),
lambda itx: itx[0].is_rational and itx[1].is_rational)
if r[True] and dom == QQ:
ex1 = Mul(*[bx**ex for bx, ex in r[False] + r[None]])
r1 = r[True]
dens = [y.q for _, y in r1]
lcmdens = reduce(lcm, dens, 1)
nums = [base**(y.p * lcmdens // y.q) for base, y in r1]
ex2 = Mul(*nums)
mp1 = minimal_polynomial(ex1, x)
# use the fact that in SymPy canonicalization products of integers
# raised to rational powers are organized in relatively prime
# bases, and that in ``base**(n/d)`` a perfect power is
# simplified with the root
mp2 = ex2.q * x**lcmdens - ex2.p
ex2 = ex2**Rational(1, lcmdens)
res = _minpoly_op_algebraic_element(Mul,
ex1,
ex2,
x,
dom,
mp1=mp1,
mp2=mp2)
else:
res = _minpoly_mul(x, dom, *ex.args)
elif ex.is_Pow:
res = _minpoly_pow(ex.base, ex.exp, x, dom)
elif ex.__class__ is C.sin:
res = _minpoly_sin(ex, x)
elif ex.__class__ is C.cos:
res = _minpoly_cos(ex, x)
elif ex.__class__ is C.exp:
res = _minpoly_exp(ex, x)
elif ex.__class__ is RootOf:
res = _minpoly_rootof(ex, x)
else:
raise NotAlgebraic("%s doesn't seem to be an algebraic element" % ex)
return res
