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e87568dd9a
float_pow(): Don't let the platform pow() raise -1.0 to an integer power anymore; at least glibc gets it wrong in some cases. Note that math.pow() will continue to deliver wrong (but platform-native) results in such cases.
127 lines
4.4 KiB
Python
127 lines
4.4 KiB
Python
import test.test_support, unittest
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class PowTest(unittest.TestCase):
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def powtest(self, type):
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if type != float:
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for i in range(-1000, 1000):
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self.assertEquals(pow(type(i), 0), 1)
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self.assertEquals(pow(type(i), 1), type(i))
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self.assertEquals(pow(type(0), 1), type(0))
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self.assertEquals(pow(type(1), 1), type(1))
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for i in range(-100, 100):
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self.assertEquals(pow(type(i), 3), i*i*i)
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pow2 = 1
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for i in range(0,31):
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self.assertEquals(pow(2, i), pow2)
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if i != 30 : pow2 = pow2*2
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for othertype in int, long:
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for i in range(-10, 0) + range(1, 10):
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ii = type(i)
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for j in range(1, 11):
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jj = -othertype(j)
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pow(ii, jj)
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for othertype in int, long, float:
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for i in range(1, 100):
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zero = type(0)
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exp = -othertype(i/10.0)
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if exp == 0:
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continue
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self.assertRaises(ZeroDivisionError, pow, zero, exp)
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il, ih = -20, 20
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jl, jh = -5, 5
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kl, kh = -10, 10
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asseq = self.assertEqual
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if type == float:
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il = 1
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asseq = self.assertAlmostEqual
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elif type == int:
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jl = 0
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elif type == long:
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jl, jh = 0, 15
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for i in range(il, ih+1):
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for j in range(jl, jh+1):
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for k in range(kl, kh+1):
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if k != 0:
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if type == float or j < 0:
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self.assertRaises(TypeError, pow, type(i), j, k)
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continue
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asseq(
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pow(type(i),j,k),
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pow(type(i),j)% type(k)
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)
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def test_powint(self):
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self.powtest(int)
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def test_powlong(self):
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self.powtest(long)
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def test_powfloat(self):
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self.powtest(float)
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def test_other(self):
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# Other tests-- not very systematic
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self.assertEquals(pow(3,3) % 8, pow(3,3,8))
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self.assertEquals(pow(3,3) % -8, pow(3,3,-8))
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self.assertEquals(pow(3,2) % -2, pow(3,2,-2))
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self.assertEquals(pow(-3,3) % 8, pow(-3,3,8))
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self.assertEquals(pow(-3,3) % -8, pow(-3,3,-8))
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self.assertEquals(pow(5,2) % -8, pow(5,2,-8))
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self.assertEquals(pow(3L,3L) % 8, pow(3L,3L,8))
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self.assertEquals(pow(3L,3L) % -8, pow(3L,3L,-8))
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self.assertEquals(pow(3L,2) % -2, pow(3L,2,-2))
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self.assertEquals(pow(-3L,3L) % 8, pow(-3L,3L,8))
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self.assertEquals(pow(-3L,3L) % -8, pow(-3L,3L,-8))
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self.assertEquals(pow(5L,2) % -8, pow(5L,2,-8))
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for i in range(-10, 11):
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for j in range(0, 6):
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for k in range(-7, 11):
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if j >= 0 and k != 0:
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self.assertEquals(
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pow(i,j) % k,
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pow(i,j,k)
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)
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if j >= 0 and k != 0:
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self.assertEquals(
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pow(long(i),j) % k,
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pow(long(i),j,k)
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)
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def test_bug643260(self):
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class TestRpow:
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def __rpow__(self, other):
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return None
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None ** TestRpow() # Won't fail when __rpow__ invoked. SF bug #643260.
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def test_bug705231(self):
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# -1.0 raised to an integer should never blow up. It did if the
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# platform pow() was buggy, and Python didn't worm around it.
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eq = self.assertEquals
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a = -1.0
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eq(pow(a, 1.23e167), 1.0)
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eq(pow(a, -1.23e167), 1.0)
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for b in range(-10, 11):
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eq(pow(a, float(b)), b & 1 and -1.0 or 1.0)
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for n in range(0, 100):
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fiveto = float(5 ** n)
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# For small n, fiveto will be odd. Eventually we run out of
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# mantissa bits, though, and thereafer fiveto will be even.
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expected = fiveto % 2.0 and -1.0 or 1.0
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eq(pow(a, fiveto), expected)
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eq(pow(a, -fiveto), expected)
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eq(expected, 1.0) # else we didn't push fiveto to evenness
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def test_main():
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test.test_support.run_unittest(PowTest)
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if __name__ == "__main__":
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test_main()
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