bpo-39479:Add math.lcm() function: Least Common Multiple (#18547)
* Update math.rst
* Update math.rst
* updated whats new
* Update test_math.py
* Update mathmodule.c
* Update mathmodule.c.h
* Update ACKS
* 📜🤖 Added by blurb_it.
* Update 3.9.rst
* Update 2020-02-18-12-37-16.bpo-39479.j3UcCq.rst
* Update math.rst
* Update 2020-02-18-12-37-16.bpo-39479.j3UcCq.rst
* Update test_math.py
* Update ACKS
* Update mathmodule.c.h
* Update mathmodule.c
* Update mathmodule.c.h
* Update mathmodule.c.h
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
diff --git a/Doc/library/math.rst b/Doc/library/math.rst
index c4c1800..d8ac352 100644
--- a/Doc/library/math.rst
+++ b/Doc/library/math.rst
@@ -136,6 +136,15 @@
.. versionadded:: 3.5
+.. function:: lcm(a, b)
+
+ Return the least common multiple of integers *a* and *b*. The value of
+ ``lcm(a, b)`` is the smallest nonnegative integer that is a multiple of
+ both *a* and *b*. If either *a* or *b* is zero then ``lcm(a, b)`` is zero.
+
+ .. versionadded:: 3.9
+
+
.. function:: isclose(a, b, *, rel_tol=1e-09, abs_tol=0.0)
Return ``True`` if the values *a* and *b* are close to each other and
diff --git a/Doc/whatsnew/3.9.rst b/Doc/whatsnew/3.9.rst
index 66eb9e7..161675d 100644
--- a/Doc/whatsnew/3.9.rst
+++ b/Doc/whatsnew/3.9.rst
@@ -216,6 +216,9 @@
math
----
+Add :func:`math.lcm`: return the least common multiple of *a* and *b*.
+(Contributed by Ananthakrishnan in :issue:`39479`.)
+
Add :func:`math.nextafter`: return the next floating-point value after *x*
towards *y*.
(Contributed by Victor Stinner in :issue:`39288`.)
diff --git a/Lib/test/test_math.py b/Lib/test/test_math.py
index b3301f6..ad8273d 100644
--- a/Lib/test/test_math.py
+++ b/Lib/test/test_math.py
@@ -974,6 +974,41 @@
with self.assertRaises(TypeError):
math.isqrt(value)
+ def test_lcm(self):
+ lcm = math.lcm
+ self.assertEqual(lcm(0, 0), 0)
+ self.assertEqual(lcm(1, 0), 0)
+ self.assertEqual(lcm(-1, 0), 0)
+ self.assertEqual(lcm(0, 1), 0)
+ self.assertEqual(lcm(0, -1), 0)
+ self.assertEqual(lcm(7, 1), 7)
+ self.assertEqual(lcm(7, -1), 7)
+ self.assertEqual(lcm(-23, 15), 345)
+ self.assertEqual(lcm(120, 84), 840)
+ self.assertEqual(lcm(84, -120), 840)
+ self.assertEqual(lcm(1216342683557601535506311712,
+ 436522681849110124616458784),
+ 16592536571065866494401400422922201534178938447014944)
+ x = 43461045657039990237
+ y = 10645022458251153277
+
+ for c in (652560,
+ 57655923087165495981):
+ a = x * c
+ b = y * c
+ d = x * y * c
+ self.assertEqual(lcm(a, b), d)
+ self.assertEqual(lcm(b, a), d)
+ self.assertEqual(lcm(-a, b), d)
+ self.assertEqual(lcm(b, -a), d)
+ self.assertEqual(lcm(a, -b), d)
+ self.assertEqual(lcm(-b, a), d)
+ self.assertEqual(lcm(-a, -b), d)
+ self.assertEqual(lcm(-b, -a), d)
+ self.assertEqual(lcm(MyIndexable(120), MyIndexable(84)), 840)
+ self.assertRaises(TypeError, lcm, 120.0, 84)
+ self.assertRaises(TypeError, lcm, 120, 84.0)
+
def testLdexp(self):
self.assertRaises(TypeError, math.ldexp)
self.ftest('ldexp(0,1)', math.ldexp(0,1), 0)
diff --git a/Misc/ACKS b/Misc/ACKS
index e8ce303..b11ee9c 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -45,6 +45,7 @@
A. Amoroso
Mark Anacker
Shashwat Anand
+Ananthakrishnan
Anders Andersen
Tycho Andersen
John Anderson
diff --git a/Misc/NEWS.d/next/Library/2020-02-18-12-37-16.bpo-39479.j3UcCq.rst b/Misc/NEWS.d/next/Library/2020-02-18-12-37-16.bpo-39479.j3UcCq.rst
new file mode 100644
index 0000000..6f16623
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-02-18-12-37-16.bpo-39479.j3UcCq.rst
@@ -0,0 +1 @@
+Add :func:`math.lcm` function: least common multiple.
diff --git a/Modules/clinic/mathmodule.c.h b/Modules/clinic/mathmodule.c.h
index f95d291..df45a1a 100644
--- a/Modules/clinic/mathmodule.c.h
+++ b/Modules/clinic/mathmodule.c.h
@@ -85,6 +85,36 @@
#define MATH_FACTORIAL_METHODDEF \
{"factorial", (PyCFunction)math_factorial, METH_O, math_factorial__doc__},
+PyDoc_STRVAR(math_lcm__doc__,
+"lcm($module, x, y, /)\n"
+"--\n"
+"\n"
+"least common multiple of x and y");
+
+#define MATH_LCM_METHODDEF \
+ {"lcm", (PyCFunction)(void(*)(void))math_lcm, METH_FASTCALL, math_lcm__doc__},
+
+static PyObject *
+math_lcm_impl(PyObject *module, PyObject *a, PyObject *b);
+
+static PyObject *
+math_lcm(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
+{
+ PyObject *return_value = NULL;
+ PyObject *a;
+ PyObject *b;
+
+ if (!_PyArg_CheckPositional("lcm", nargs, 2, 2)) {
+ goto exit;
+ }
+ a = args[0];
+ b = args[1];
+ return_value = math_lcm_impl(module, a, b);
+
+exit:
+ return return_value;
+}
+
PyDoc_STRVAR(math_trunc__doc__,
"trunc($module, x, /)\n"
"--\n"
@@ -895,4 +925,4 @@
exit:
return return_value;
}
-/*[clinic end generated code: output=9b51d215dbcac060 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=f8daa185c043a7b7 input=a9049054013a1b77]*/
diff --git a/Modules/mathmodule.c b/Modules/mathmodule.c
index 309f229..f74b7e1 100644
--- a/Modules/mathmodule.c
+++ b/Modules/mathmodule.c
@@ -2018,6 +2018,59 @@
/*[clinic input]
+math.lcm
+ x as a: object
+ y as b: object
+ /
+least common multiple of x and y
+[clinic start generated code]*/
+
+static PyObject *
+math_lcm_impl(PyObject *module, PyObject *a, PyObject *b)
+/*[clinic end generated code: output=6f83fb6d671074ba input=efb3d7b7334b7118]*/
+{
+ PyObject *g, *m, *f, *ab;
+
+ a = PyNumber_Index(a);
+ if (a == NULL) {
+ return NULL;
+ }
+ b = PyNumber_Index(b);
+ if (b == NULL) {
+ Py_DECREF(a);
+ return NULL;
+ }
+ if (_PyLong_Sign(a) == 0 || _PyLong_Sign(b) == 0) {
+ Py_DECREF(a);
+ Py_DECREF(b);
+ return PyLong_FromLong(0);
+ }
+ g = _PyLong_GCD(a, b);
+ if (g == NULL) {
+ Py_DECREF(a);
+ Py_DECREF(b);
+ return NULL;
+ }
+ f = PyNumber_FloorDivide(a, g);
+ Py_DECREF(g);
+ Py_DECREF(a);
+ if (f == NULL) {
+ Py_DECREF(b);
+ return NULL;
+ }
+ m = PyNumber_Multiply(f, b);
+ Py_DECREF(f);
+ Py_DECREF(b);
+ if (m == NULL) {
+ return NULL;
+ }
+ ab = PyNumber_Absolute(m);
+ Py_DECREF(m);
+ return ab;
+}
+
+
+/*[clinic input]
math.trunc
x: object
@@ -3362,6 +3415,7 @@
MATH_ISINF_METHODDEF
MATH_ISNAN_METHODDEF
MATH_ISQRT_METHODDEF
+ MATH_LCM_METHODDEF
MATH_LDEXP_METHODDEF
{"lgamma", math_lgamma, METH_O, math_lgamma_doc},
MATH_LOG_METHODDEF