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c:\python24\lib \ test \ test_pow.py



0001 import test.test_support, unittest
0002 
0003 class PowTest(unittest.TestCase):
0004 
0005     def powtest(self, type):
0006         if type != float:
0007             for i in range(-1000, 1000):
0008                 self.assertEquals(pow(type(i), 0), 1)
0009                 self.assertEquals(pow(type(i), 1), type(i))
0010                 self.assertEquals(pow(type(0), 1), type(0))
0011                 self.assertEquals(pow(type(1), 1), type(1))
0012 
0013             for i in range(-100, 100):
0014                 self.assertEquals(pow(type(i), 3), i*i*i)
0015 
0016             pow2 = 1
0017             for i in range(0,31):
0018                 self.assertEquals(pow(2, i), pow2)
0019                 if i != 30 : pow2 = pow2*2
0020 
0021             for othertype in int, long:
0022                 for i in range(-10, 0) + range(1, 10):
0023                     ii = type(i)
0024                     for j in range(1, 11):
0025                         jj = -othertype(j)
0026                         pow(ii, jj)
0027 
0028         for othertype in int, long, float:
0029             for i in range(1, 100):
0030                 zero = type(0)
0031                 exp = -othertype(i/10.0)
0032                 if exp == 0:
0033                     continue
0034                 self.assertRaises(ZeroDivisionError, pow, zero, exp)
0035 
0036         il, ih = -20, 20
0037         jl, jh = -5,   5
0038         kl, kh = -10, 10
0039         asseq = self.assertEqual
0040         if type == float:
0041             il = 1
0042             asseq = self.assertAlmostEqual
0043         elif type == int:
0044             jl = 0
0045         elif type == long:
0046             jl, jh = 0, 15
0047         for i in range(il, ih+1):
0048             for j in range(jl, jh+1):
0049                 for k in range(kl, kh+1):
0050                     if k != 0:
0051                         if type == float or j < 0:
0052                             self.assertRaises(TypeError, pow, type(i), j, k)
0053                             continue
0054                         asseq(
0055                             pow(type(i),j,k),
0056                             pow(type(i),j)% type(k)
0057                         )
0058 
0059     def test_powint(self):
0060         self.powtest(int)
0061 
0062     def test_powlong(self):
0063         self.powtest(long)
0064 
0065     def test_powfloat(self):
0066         self.powtest(float)
0067 
0068     def test_other(self):
0069         # Other tests-- not very systematic
0070         self.assertEquals(pow(3,3) % 8, pow(3,3,8))
0071         self.assertEquals(pow(3,3) % -8, pow(3,3,-8))
0072         self.assertEquals(pow(3,2) % -2, pow(3,2,-2))
0073         self.assertEquals(pow(-3,3) % 8, pow(-3,3,8))
0074         self.assertEquals(pow(-3,3) % -8, pow(-3,3,-8))
0075         self.assertEquals(pow(5,2) % -8, pow(5,2,-8))
0076 
0077         self.assertEquals(pow(3L,3L) % 8, pow(3L,3L,8))
0078         self.assertEquals(pow(3L,3L) % -8, pow(3L,3L,-8))
0079         self.assertEquals(pow(3L,2) % -2, pow(3L,2,-2))
0080         self.assertEquals(pow(-3L,3L) % 8, pow(-3L,3L,8))
0081         self.assertEquals(pow(-3L,3L) % -8, pow(-3L,3L,-8))
0082         self.assertEquals(pow(5L,2) % -8, pow(5L,2,-8))
0083 
0084         for i in range(-10, 11):
0085             for j in range(0, 6):
0086                 for k in range(-7, 11):
0087                     if j >= 0 and k != 0:
0088                         self.assertEquals(
0089                             pow(i,j) % k,
0090                             pow(i,j,k)
0091                         )
0092                     if j >= 0 and k != 0:
0093                         self.assertEquals(
0094                             pow(long(i),j) % k,
0095                             pow(long(i),j,k)
0096                         )
0097 
0098     def test_bug643260(self):
0099         class TestRpow:
0100             def __rpow__(self, other):
0101                 return None
0102         None ** TestRpow() # Won't fail when __rpow__ invoked.  SF bug #643260.
0103 
0104     def test_bug705231(self):
0105         # -1.0 raised to an integer should never blow up.  It did if the
0106         # platform pow() was buggy, and Python didn't worm around it.
0107         eq = self.assertEquals
0108         a = -1.0
0109         eq(pow(a, 1.23e167), 1.0)
0110         eq(pow(a, -1.23e167), 1.0)
0111         for b in range(-10, 11):
0112             eq(pow(a, float(b)), b & 1 and -1.0 or 1.0)
0113         for n in range(0, 100):
0114             fiveto = float(5 ** n)
0115             # For small n, fiveto will be odd.  Eventually we run out of
0116             # mantissa bits, though, and thereafer fiveto will be even.
0117             expected = fiveto % 2.0 and -1.0 or 1.0
0118             eq(pow(a, fiveto), expected)
0119             eq(pow(a, -fiveto), expected)
0120         eq(expected, 1.0)   # else we didn't push fiveto to evenness
0121 
0122 def test_main():
0123     test.test_support.run_unittest(PowTest)
0124 
0125 if __name__ == "__main__":
0126     test_main()
0127 

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