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author | Raymond Hettinger <python@rcn.com> | 2008-01-25 01:23:38 +0000 |
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committer | Raymond Hettinger <python@rcn.com> | 2008-01-25 01:23:38 +0000 |
commit | 9c6d81f5dd083ad536106bf723f705d70ddbe258 (patch) | |
tree | 3f5956a0a872004383221faf5465d6716be3db29 | |
parent | 7ea82253ea6ed6d8930630f5b786489ff8817dcb (diff) | |
download | cpython-git-9c6d81f5dd083ad536106bf723f705d70ddbe258.tar.gz |
Fix-up signature for approximation.
-rwxr-xr-x | Lib/rational.py | 11 | ||||
-rw-r--r-- | Lib/test/test_rational.py | 8 |
2 files changed, 10 insertions, 9 deletions
diff --git a/Lib/rational.py b/Lib/rational.py index 40b91635d3..d23f433969 100755 --- a/Lib/rational.py +++ b/Lib/rational.py @@ -195,16 +195,17 @@ class Rational(RationalAbc): n, d = d, n return cf - @classmethod - def approximate_from_float(cls, f, max_denominator): - 'Best rational approximation to f with a denominator <= max_denominator' + def approximate(self, max_denominator): + 'Best rational approximation with a denominator <= max_denominator' # XXX First cut at algorithm # Still needs rounding rules as specified at # http://en.wikipedia.org/wiki/Continued_fraction - cf = cls.from_float(f).as_continued_fraction() + if self.denominator <= max_denominator: + return self + cf = self.as_continued_fraction() result = Rational(0) for i in range(1, len(cf)): - new = cls.from_continued_fraction(cf[:i]) + new = self.from_continued_fraction(cf[:i]) if new.denominator > max_denominator: break result = new diff --git a/Lib/test/test_rational.py b/Lib/test/test_rational.py index 20abce26df..6ce7c35c37 100644 --- a/Lib/test/test_rational.py +++ b/Lib/test/test_rational.py @@ -155,10 +155,10 @@ class RationalTest(unittest.TestCase): [-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): - 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 testApproximateFrom(self): + self.assertEqual(R.from_float(math.pi).approximate(10000), R(355, 113)) + self.assertEqual(R.from_float(-math.pi).approximate(10000), R(-355, 113)) + self.assertEqual(R.from_float(0.0).approximate(10000), R(0)) def testConversions(self): self.assertTypedEquals(-1, trunc(R(-11, 10))) |