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Modules/_decimal/tests/bignum.py
42 строки
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Stefan Krah
Use zero bottom margin.
22 авг 2012, 21:28
22 авг 2012, 21:28
17183a2
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# # These tests require gmpy and test the limits of the 32-bit build. The # limits of the 64-bit build are so large that they cannot be tested # on accessible hardware. # import sys from decimal import * from gmpy import mpz _PyHASH_MODULUS = sys.hash_info.modulus # hash values to use for positive and negative infinities, and nans _PyHASH_INF = sys.hash_info.inf _PyHASH_NAN = sys.hash_info.nan # _PyHASH_10INV is the inverse of 10 modulo the prime _PyHASH_MODULUS _PyHASH_10INV = pow(10, _PyHASH_MODULUS - 2, _PyHASH_MODULUS) def xhash(coeff, exp): sign = 1 if coeff < 0: sign = -1 coeff = -coeff if exp >= 0: exp_hash = pow(10, exp, _PyHASH_MODULUS) else: exp_hash = pow(_PyHASH_10INV, -exp, _PyHASH_MODULUS) hash_ = coeff * exp_hash % _PyHASH_MODULUS ans = hash_ if sign == 1 else -hash_ return -2 if ans == -1 else ans x = mpz(10) ** 425000000 - 1 coeff = int(x) d = Decimal('9' * 425000000 + 'e-849999999') h1 = xhash(coeff, -849999999) h2 = hash(d) assert h2 == h1