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Minor clean-up and more tests.

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This commit is contained in:
Raymond Hettinger 2008-01-24 02:00:25 +00:00
parent cf10926088
commit eb461904eb
2 changed files with 15 additions and 2 deletions
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6
Lib/rational.py
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@ -179,7 +179,9 @@ class Rational(RationalAbc):
for e in reversed(seq): for e in reversed(seq):
n, d = d, n n, d = d, n
n += e * d n += e * d
return cls(n, d) if seq:
return cls(n, d)
return cls(0)
def as_continued_fraction(self): def as_continued_fraction(self):
'Return continued fraction expressed as a list' 'Return continued fraction expressed as a list'
@ -200,7 +202,7 @@ class Rational(RationalAbc):
# Still needs rounding rules as specified at # Still needs rounding rules as specified at
# http://en.wikipedia.org/wiki/Continued_fraction # http://en.wikipedia.org/wiki/Continued_fraction
cf = cls.from_float(f).as_continued_fraction() cf = cls.from_float(f).as_continued_fraction()
result = new = Rational(0, 1) result = Rational(0)
for i in range(1, len(cf)): for i in range(1, len(cf)):
new = cls.from_continued_fraction(cf[:i]) new = cls.from_continued_fraction(cf[:i])
if new.denominator > max_denominator: if new.denominator > max_denominator:

11
Lib/test/test_rational.py
View file

@ -140,12 +140,23 @@ class RationalTest(unittest.TestCase):
phi = R.from_continued_fraction([1]*100) phi = R.from_continued_fraction([1]*100)
self.assertEquals(round(phi - (1 + 5 ** 0.5) / 2, 10), 0.0) self.assertEquals(round(phi - (1 + 5 ** 0.5) / 2, 10), 0.0)
minusphi = R.from_continued_fraction([-1]*100)
self.assertEquals(round(minusphi + (1 + 5 ** 0.5) / 2, 10), 0.0)
self.assertEquals(R.from_continued_fraction([0]), R(0))
self.assertEquals(R.from_continued_fraction([]), R(0))
def testAsContinuedFraction(self): def testAsContinuedFraction(self):
self.assertEqual(R.from_float(math.pi).as_continued_fraction()[:15], self.assertEqual(R.from_float(math.pi).as_continued_fraction()[:15],
[3, 7, 15, 1, 292, 1, 1, 1, 2, 1, 3, 1, 14, 3, 3]) [3, 7, 15, 1, 292, 1, 1, 1, 2, 1, 3, 1, 14, 3, 3])
self.assertEqual(R.from_float(-math.pi).as_continued_fraction()[:16],
[-4, 1, 6, 15, 1, 292, 1, 1, 1, 2, 1, 3, 1, 14, 3, 3])
self.assertEqual(R(0).as_continued_fraction(), [0])
def testApproximateFromFloat(self): def testApproximateFromFloat(self):
self.assertEqual(R.approximate_from_float(math.pi, 10000), R(355, 113)) self.assertEqual(R.approximate_from_float(math.pi, 10000), R(355, 113))
self.assertEqual(R.approximate_from_float(-math.pi, 10000), R(-355, 113))
self.assertEqual(R.approximate_from_float(0.0, 10000), R(0))
def testConversions(self): def testConversions(self):
self.assertTypedEquals(-1, trunc(R(-11, 10))) self.assertTypedEquals(-1, trunc(R(-11, 10)))