diff --git a/Lib/test/test_math.py b/Lib/test/test_math.py index faf11e6887b..0d35130e604 100644 --- a/Lib/test/test_math.py +++ b/Lib/test/test_math.py @@ -102,7 +102,7 @@ class MathTests(unittest.TestCase): self.ftest('atan(0)', math.atan(0), 0) self.ftest('atan(1)', math.atan(1), math.pi/4) self.ftest('atan(inf)', math.atan(INF), math.pi/2) - self.ftest('atan(-inf)', math.atan(-INF), -math.pi/2) + self.ftest('atan(-inf)', math.atan(NINF), -math.pi/2) self.assert_(math.isnan(math.atan(NAN))) def testAtanh(self): @@ -387,14 +387,128 @@ class MathTests(unittest.TestCase): self.assert_(math.isnan(math.pow(2, NAN))) self.assert_(math.isnan(math.pow(0, NAN))) self.assertEqual(math.pow(1, NAN), 1) - self.assertEqual(1**NAN, 1) - self.assertEqual(1**INF, 1) - self.assertEqual(1**NINF, 1) - self.assertEqual(1**0, 1) - self.assertEqual(1.**NAN, 1) - self.assertEqual(1.**INF, 1) - self.assertEqual(1.**NINF, 1) - self.assertEqual(1.**0, 1) + + # pow(0., x) + self.assertEqual(math.pow(0., INF), 0.) + self.assertEqual(math.pow(0., 3.), 0.) + self.assertEqual(math.pow(0., 2.3), 0.) + self.assertEqual(math.pow(0., 2.), 0.) + self.assertEqual(math.pow(0., 0.), 1.) + self.assertEqual(math.pow(0., -0.), 1.) + self.assertRaises(ValueError, math.pow, 0., -2.) + self.assertRaises(ValueError, math.pow, 0., -2.3) + self.assertRaises(ValueError, math.pow, 0., -3.) + self.assertRaises(ValueError, math.pow, 0., NINF) + self.assert_(math.isnan(math.pow(0., NAN))) + + # pow(INF, x) + self.assertEqual(math.pow(INF, INF), INF) + self.assertEqual(math.pow(INF, 3.), INF) + self.assertEqual(math.pow(INF, 2.3), INF) + self.assertEqual(math.pow(INF, 2.), INF) + self.assertEqual(math.pow(INF, 0.), 1.) + self.assertEqual(math.pow(INF, -0.), 1.) + self.assertEqual(math.pow(INF, -2.), 0.) + self.assertEqual(math.pow(INF, -2.3), 0.) + self.assertEqual(math.pow(INF, -3.), 0.) + self.assertEqual(math.pow(INF, NINF), 0.) + self.assert_(math.isnan(math.pow(INF, NAN))) + + # pow(-0., x) + self.assertEqual(math.pow(-0., INF), 0.) + self.assertEqual(math.pow(-0., 3.), -0.) + self.assertEqual(math.pow(-0., 2.3), 0.) + self.assertEqual(math.pow(-0., 2.), 0.) + self.assertEqual(math.pow(-0., 0.), 1.) + self.assertEqual(math.pow(-0., -0.), 1.) + self.assertRaises(ValueError, math.pow, -0., -2.) + self.assertRaises(ValueError, math.pow, -0., -2.3) + self.assertRaises(ValueError, math.pow, -0., -3.) + self.assertRaises(ValueError, math.pow, -0., NINF) + self.assert_(math.isnan(math.pow(-0., NAN))) + + # pow(NINF, x) + self.assertEqual(math.pow(NINF, INF), INF) + self.assertEqual(math.pow(NINF, 3.), NINF) + self.assertEqual(math.pow(NINF, 2.3), INF) + self.assertEqual(math.pow(NINF, 2.), INF) + self.assertEqual(math.pow(NINF, 0.), 1.) + self.assertEqual(math.pow(NINF, -0.), 1.) + self.assertEqual(math.pow(NINF, -2.), 0.) + self.assertEqual(math.pow(NINF, -2.3), 0.) + self.assertEqual(math.pow(NINF, -3.), -0.) + self.assertEqual(math.pow(NINF, NINF), 0.) + self.assert_(math.isnan(math.pow(NINF, NAN))) + + # pow(-1, x) + self.assertEqual(math.pow(-1., INF), 1.) + self.assertEqual(math.pow(-1., 3.), -1.) + self.assertRaises(ValueError, math.pow, -1., 2.3) + self.assertEqual(math.pow(-1., 2.), 1.) + self.assertEqual(math.pow(-1., 0.), 1.) + self.assertEqual(math.pow(-1., -0.), 1.) + self.assertEqual(math.pow(-1., -2.), 1.) + self.assertRaises(ValueError, math.pow, -1., -2.3) + self.assertEqual(math.pow(-1., -3.), -1.) + self.assertEqual(math.pow(-1., NINF), 1.) + self.assert_(math.isnan(math.pow(-1., NAN))) + + # pow(1, x) + self.assertEqual(math.pow(1., INF), 1.) + self.assertEqual(math.pow(1., 3.), 1.) + self.assertEqual(math.pow(1., 2.3), 1.) + self.assertEqual(math.pow(1., 2.), 1.) + self.assertEqual(math.pow(1., 0.), 1.) + self.assertEqual(math.pow(1., -0.), 1.) + self.assertEqual(math.pow(1., -2.), 1.) + self.assertEqual(math.pow(1., -2.3), 1.) + self.assertEqual(math.pow(1., -3.), 1.) + self.assertEqual(math.pow(1., NINF), 1.) + self.assertEqual(math.pow(1., NAN), 1.) + + # pow(x, 0) should be 1 for any x + self.assertEqual(math.pow(2.3, 0.), 1.) + self.assertEqual(math.pow(-2.3, 0.), 1.) + self.assertEqual(math.pow(NAN, 0.), 1.) + self.assertEqual(math.pow(2.3, -0.), 1.) + self.assertEqual(math.pow(-2.3, -0.), 1.) + self.assertEqual(math.pow(NAN, -0.), 1.) + + # pow(x, y) is invalid if x is negative and y is not integral + self.assertRaises(ValueError, math.pow, -1., 2.3) + self.assertRaises(ValueError, math.pow, -15., -3.1) + + # pow(x, NINF) + self.assertEqual(math.pow(1.9, NINF), 0.) + self.assertEqual(math.pow(1.1, NINF), 0.) + self.assertEqual(math.pow(0.9, NINF), INF) + self.assertEqual(math.pow(0.1, NINF), INF) + self.assertEqual(math.pow(-0.1, NINF), INF) + self.assertEqual(math.pow(-0.9, NINF), INF) + self.assertEqual(math.pow(-1.1, NINF), 0.) + self.assertEqual(math.pow(-1.9, NINF), 0.) + + # pow(x, INF) + self.assertEqual(math.pow(1.9, INF), INF) + self.assertEqual(math.pow(1.1, INF), INF) + self.assertEqual(math.pow(0.9, INF), 0.) + self.assertEqual(math.pow(0.1, INF), 0.) + self.assertEqual(math.pow(-0.1, INF), 0.) + self.assertEqual(math.pow(-0.9, INF), 0.) + self.assertEqual(math.pow(-1.1, INF), INF) + self.assertEqual(math.pow(-1.9, INF), INF) + + # the following tests have been commented out since they don't + # really belong here: the implementation of ** for floats is + # independent of the implemention of math.pow + #self.assertEqual(1**NAN, 1) + #self.assertEqual(1**INF, 1) + #self.assertEqual(1**NINF, 1) + #self.assertEqual(1**0, 1) + #self.assertEqual(1.**NAN, 1) + #self.assertEqual(1.**INF, 1) + #self.assertEqual(1.**NINF, 1) + #self.assertEqual(1.**0, 1) def testRadians(self): self.assertRaises(TypeError, math.radians) @@ -421,7 +535,7 @@ class MathTests(unittest.TestCase): self.ftest('sinh(1)**2-cosh(1)**2', math.sinh(1)**2-math.cosh(1)**2, -1) self.ftest('sinh(1)+sinh(-1)', math.sinh(1)+math.sinh(-1), 0) self.assertEquals(math.sinh(INF), INF) - self.assertEquals(math.sinh(-INF), -INF) + self.assertEquals(math.sinh(NINF), NINF) self.assert_(math.isnan(math.sinh(NAN))) def testSqrt(self): diff --git a/Modules/mathmodule.c b/Modules/mathmodule.c index 56b52fd7b0f..a78b6988dcb 100644 --- a/Modules/mathmodule.c +++ b/Modules/mathmodule.c @@ -513,6 +513,7 @@ math_pow(PyObject *self, PyObject *args) { PyObject *ox, *oy; double r, x, y; + int y_is_odd; if (! PyArg_UnpackTuple(args, "pow", 2, 2, &ox, &oy)) return NULL; @@ -523,6 +524,16 @@ math_pow(PyObject *self, PyObject *args) /* 1**x and x**0 return 1., even if x is a NaN or infinity. */ if (x == 1.0 || y == 0.0) return PyFloat_FromDouble(1.); + /* inf ** (nonzero, non-NaN) is one of +-0, +-infinity */ + if (Py_IS_INFINITY(x) && !Py_IS_NAN(y)) { + y_is_odd = Py_IS_FINITE(y) && fmod(fabs(y), 2.0) == 1.0; + if (y > 0.) + r = y_is_odd ? x : fabs(x); + else + r = y_is_odd ? copysign(0., x) : 0.; + return PyFloat_FromDouble(r); + } + errno = 0; PyFPE_START_PROTECT("in math_pow", return 0); r = pow(x, y);