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bpo-44357:Add math.cbrt() function: Cube Root (GH-26622)

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* Add math.cbrt() function: Cube Root

Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Mark Dickinson <dickinsm@gmail.com>
This commit is contained in:
Ajith Ramachandran 2021-06-10 22:12:09 +05:30 • committed by GitHub
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commit ac867f10b4
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7
Doc/library/math.rst
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@ -342,6 +342,13 @@ necessarily has no fractional bits.
Power and logarithmic functions
-------------------------------
.. function:: cbrt(x)
Return the cube root of *x*.
.. versionadded:: 3.11
.. function:: exp(x)
Return *e* raised to the power *x*, where *e* = 2.718281... is the base

7
Doc/whatsnew/3.11.rst
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@ -93,6 +93,13 @@ Support :PEP:`515`-style initialization of :class:`~fractions.Fraction` from
string. (Contributed by Sergey B Kirpichev in :issue:`44258`.)
math
----
Add :func:`math.cbrt()`: return the cube root of x.
(Contributed by Ajith Ramachandran in :issue:`44357`.)
Removed
=======
* :class:`smtpd.MailmanProxy` is now removed as it is unusable without

16
Lib/test/test_math.py
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@ -377,6 +377,22 @@ class MathTests(unittest.TestCase):
self.assertTrue(math.isnan(math.atan2(NAN, INF)))
self.assertTrue(math.isnan(math.atan2(NAN, NAN)))
def testCbrt(self):
self.assertRaises(TypeError, math.cbrt)
self.ftest('cbrt(0)', math.cbrt(0), 0)
self.ftest('cbrt(1)', math.cbrt(1), 1)
self.ftest('cbrt(8)', math.cbrt(8), 2)
self.ftest('cbrt(0.0)', math.cbrt(0.0), 0.0)
self.ftest('cbrt(-0.0)', math.cbrt(-0.0), -0.0)
self.ftest('cbrt(1.2)', math.cbrt(1.2), 1.062658569182611)
self.ftest('cbrt(-2.6)', math.cbrt(-2.6), -1.375068867074141)
self.ftest('cbrt(27)', math.cbrt(27), 3)
self.ftest('cbrt(-1)', math.cbrt(-1), -1)
self.ftest('cbrt(-27)', math.cbrt(-27), -3)
self.assertEqual(math.cbrt(INF), INF)
self.assertEqual(math.cbrt(NINF), NINF)
self.assertTrue(math.isnan(math.cbrt(NAN)))
def testCeil(self):
self.assertRaises(TypeError, math.ceil)
self.assertEqual(int, type(math.ceil(0.5)))

1
Misc/ACKS
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@ -1415,6 +1415,7 @@ Jérôme Radix
Burton Radons
Abhilash Raj
Shorya Raj
Ajith Ramachandran
Dhushyanth Ramasamy
Ashwin Ramaswami
Jeff Ramnani

1
Misc/NEWS.d/next/Library/2021-06-09-08-32-39.bpo-44357.70Futb.rst Normal file
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@ -0,0 +1 @@
Added a function that returns cube root of the given number :func:`math.cbrt`

4
Modules/mathmodule.c
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@ -1182,6 +1182,9 @@ FUNC2(atan2, m_atan2,
FUNC1(atanh, m_atanh, 0,
"atanh($module, x, /)\n--\n\n"
"Return the inverse hyperbolic tangent of x.")
FUNC1(cbrt, cbrt, 0,
"cbrt($module, x, /)\n--\n\n"
"Return the cube root of x.")
/*[clinic input]
math.ceil
@ -3550,6 +3553,7 @@ static PyMethodDef math_methods[] = {
{"atan", math_atan, METH_O, math_atan_doc},
{"atan2", (PyCFunction)(void(*)(void))math_atan2, METH_FASTCALL, math_atan2_doc},
{"atanh", math_atanh, METH_O, math_atanh_doc},
{"cbrt", math_cbrt, METH_O, math_cbrt_doc},
MATH_CEIL_METHODDEF
{"copysign", (PyCFunction)(void(*)(void))math_copysign, METH_FASTCALL, math_copysign_doc},
{"cos", math_cos, METH_O, math_cos_doc},