forked from sympy/sympy
/
rational.py
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/
rational.py
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import operator
import sys
from .libmp import int_types, mpf_hash, bitcount, from_man_exp, HASH_MODULUS
new = object.__new__
def create_reduced(p, q, _cache={}):
key = p, q
if key in _cache:
return _cache[key]
x, y = p, q
while y:
x, y = y, x % y
if x != 1:
p //= x
q //= x
v = new(mpq)
v._mpq_ = p, q
# Speedup integers, half-integers and other small fractions
if q <= 4 and abs(key[0]) < 100:
_cache[key] = v
return v
class mpq(object):
"""
Exact rational type, currently only intended for internal use.
"""
__slots__ = ["_mpq_"]
def __new__(cls, p, q=1):
if type(p) is tuple:
p, q = p
elif hasattr(p, '_mpq_'):
p, q = p._mpq_
return create_reduced(p, q)
def __repr__(s):
return "mpq(%s,%s)" % s._mpq_
def __str__(s):
return "(%s/%s)" % s._mpq_
def __int__(s):
a, b = s._mpq_
return a // b
def __nonzero__(s):
return bool(s._mpq_[0])
__bool__ = __nonzero__
def __hash__(s):
a, b = s._mpq_
if sys.version >= "3.2":
inverse = pow(b, HASH_MODULUS-2, HASH_MODULUS)
if not inverse:
h = sys.hash_info.inf
else:
h = (abs(a) * inverse) % HASH_MODULUS
if a < 0: h = -h
if h == -1: h = -2
return h
else:
if b == 1:
return hash(a)
# Power of two: mpf compatible hash
if not (b & (b-1)):
return mpf_hash(from_man_exp(a, 1-bitcount(b)))
return hash((a,b))
def __eq__(s, t):
ttype = type(t)
if ttype is mpq:
return s._mpq_ == t._mpq_
if ttype in int_types:
a, b = s._mpq_
if b != 1:
return False
return a == t
return NotImplemented
def __ne__(s, t):
ttype = type(t)
if ttype is mpq:
return s._mpq_ != t._mpq_
if ttype in int_types:
a, b = s._mpq_
if b != 1:
return True
return a != t
return NotImplemented
def _cmp(s, t, op):
ttype = type(t)
if ttype in int_types:
a, b = s._mpq_
return op(a, t*b)
if ttype is mpq:
a, b = s._mpq_
c, d = t._mpq_
return op(a*d, b*c)
return NotImplementedError
def __lt__(s, t): return s._cmp(t, operator.lt)
def __le__(s, t): return s._cmp(t, operator.le)
def __gt__(s, t): return s._cmp(t, operator.gt)
def __ge__(s, t): return s._cmp(t, operator.ge)
def __abs__(s):
a, b = s._mpq_
if a >= 0:
return s
v = new(mpq)
v._mpq_ = -a, b
return v
def __neg__(s):
a, b = s._mpq_
v = new(mpq)
v._mpq_ = -a, b
return v
def __pos__(s):
return s
def __add__(s, t):
ttype = type(t)
if ttype is mpq:
a, b = s._mpq_
c, d = t._mpq_
return create_reduced(a*d+b*c, b*d)
if ttype in int_types:
a, b = s._mpq_
v = new(mpq)
v._mpq_ = a+b*t, b
return v
return NotImplemented
__radd__ = __add__
def __sub__(s, t):
ttype = type(t)
if ttype is mpq:
a, b = s._mpq_
c, d = t._mpq_
return create_reduced(a*d-b*c, b*d)
if ttype in int_types:
a, b = s._mpq_
v = new(mpq)
v._mpq_ = a-b*t, b
return v
return NotImplemented
def __rsub__(s, t):
ttype = type(t)
if ttype is mpq:
a, b = s._mpq_
c, d = t._mpq_
return create_reduced(b*c-a*d, b*d)
if ttype in int_types:
a, b = s._mpq_
v = new(mpq)
v._mpq_ = b*t-a, b
return v
return NotImplemented
def __mul__(s, t):
ttype = type(t)
if ttype is mpq:
a, b = s._mpq_
c, d = t._mpq_
return create_reduced(a*c, b*d)
if ttype in int_types:
a, b = s._mpq_
return create_reduced(a*t, b)
return NotImplemented
__rmul__ = __mul__
def __div__(s, t):
ttype = type(t)
if ttype is mpq:
a, b = s._mpq_
c, d = t._mpq_
return create_reduced(a*d, b*c)
if ttype in int_types:
a, b = s._mpq_
return create_reduced(a, b*t)
return NotImplemented
def __rdiv__(s, t):
ttype = type(t)
if ttype is mpq:
a, b = s._mpq_
c, d = t._mpq_
return create_reduced(b*c, a*d)
if ttype in int_types:
a, b = s._mpq_
return create_reduced(b*t, a)
return NotImplemented
def __pow__(s, t):
ttype = type(t)
if ttype in int_types:
a, b = s._mpq_
if t:
if t < 0:
a, b, t = b, a, -t
v = new(mpq)
v._mpq_ = a**t, b**t
return v
raise ZeroDivisionError
return NotImplemented
mpq_1 = mpq((1,1))
mpq_0 = mpq((0,1))
mpq_1_2 = mpq((1,2))
mpq_3_2 = mpq((3,2))
mpq_1_4 = mpq((1,4))
mpq_1_16 = mpq((1,16))
mpq_3_16 = mpq((3,16))
mpq_5_2 = mpq((5,2))
mpq_3_4 = mpq((3,4))
mpq_7_4 = mpq((7,4))
mpq_5_4 = mpq((5,4))