Added math.isinf() and math.isnan()
diff --git a/Doc/library/math.rst b/Doc/library/math.rst
index f92610f..d0b03ed 100644
--- a/Doc/library/math.rst
+++ b/Doc/library/math.rst
@@ -66,6 +66,23 @@
apart" the internal representation of a float in a portable way.
+.. function:: isinf(x)
+
+ Checks if the float *x* is positive or negative infinite.
+
+ ..versionadded:: 2.6
+
+
+.. function:: isnan(x)
+
+ Checks if the float *x* is a NaN (not a number). NaNs are part of the
+ IEEE 754 standards. Operation like but not limited to ``inf * 0``,
+ ``inf / inf`` or any operation involving a NaN, e.g. ``nan * 1``, return
+ a NaN.
+
+ ..versionadded:: 2.6
+
+
.. function:: ldexp(x, i)
Return ``x * (2**i)``. This is essentially the inverse of function
diff --git a/Lib/test/test_math.py b/Lib/test/test_math.py
index 98e4623..d2da59b 100644
--- a/Lib/test/test_math.py
+++ b/Lib/test/test_math.py
@@ -229,6 +229,22 @@
self.ftest('tanh(0)', math.tanh(0), 0)
self.ftest('tanh(1)+tanh(-1)', math.tanh(1)+math.tanh(-1), 0)
+ def testIsnan(self):
+ self.assert_(math.isnan(float("nan")))
+ self.assert_(math.isnan(float("inf")* 0.))
+ self.failIf(math.isnan(float("inf")))
+ self.failIf(math.isnan(0.))
+ self.failIf(math.isnan(1.))
+
+ def testIsinf(self):
+ self.assert_(math.isinf(float("inf")))
+ self.assert_(math.isinf(float("-inf")))
+ self.assert_(math.isinf(1E400))
+ self.assert_(math.isinf(-1E400))
+ self.failIf(math.isinf(float("nan")))
+ self.failIf(math.isinf(0.))
+ self.failIf(math.isinf(1.))
+
# RED_FLAG 16-Oct-2000 Tim
# While 2.0 is more consistent about exceptions than previous releases, it
# still fails this part of the test on some platforms. For now, we only
diff --git a/Misc/NEWS b/Misc/NEWS
index 3e3f074..95845b6 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,8 @@
Core and builtins
-----------------
+- Issue #1640: Added math.isinf() and math.isnan() functions.
+
- Issue #1726: Remove Python/atof.c from PCBuild/pythoncore.vcproj
- Removed PCbuild8/ directory and added a new build directory for VS 2005
diff --git a/Modules/mathmodule.c b/Modules/mathmodule.c
index 431590c..7540b5d 100644
--- a/Modules/mathmodule.c
+++ b/Modules/mathmodule.c
@@ -315,9 +315,8 @@
PyDoc_STRVAR(math_log10_doc,
"log10(x) -> the base 10 logarithm of x.");
-/* XXX(nnorwitz): Should we use the platform M_PI or something more accurate
- like: 3.14159265358979323846264338327950288 */
-static const double degToRad = 3.141592653589793238462643383 / 180.0;
+static const double degToRad = Py_MATH_PI / 180.0;
+static const double radToDeg = 180.0 / Py_MATH_PI;
static PyObject *
math_degrees(PyObject *self, PyObject *arg)
@@ -325,7 +324,7 @@
double x = PyFloat_AsDouble(arg);
if (x == -1.0 && PyErr_Occurred())
return NULL;
- return PyFloat_FromDouble(x / degToRad);
+ return PyFloat_FromDouble(x * radToDeg);
}
PyDoc_STRVAR(math_degrees_doc,
@@ -343,6 +342,33 @@
PyDoc_STRVAR(math_radians_doc,
"radians(x) -> converts angle x from degrees to radians");
+static PyObject *
+math_isnan(PyObject *self, PyObject *arg)
+{
+ double x = PyFloat_AsDouble(arg);
+ if (x == -1.0 && PyErr_Occurred())
+ return NULL;
+ return PyBool_FromLong((long)Py_IS_NAN(x));
+}
+
+PyDoc_STRVAR(math_isnan_doc,
+"isnan(x) -> bool\n\
+Checks if float x is not a number (NaN)");
+
+static PyObject *
+math_isinf(PyObject *self, PyObject *arg)
+{
+ double x = PyFloat_AsDouble(arg);
+ if (x == -1.0 && PyErr_Occurred())
+ return NULL;
+ return PyBool_FromLong((long)Py_IS_INFINITY(x));
+}
+
+PyDoc_STRVAR(math_isinf_doc,
+"isinf(x) -> bool\n\
+Checks if float x is infinite (positive or negative)");
+
+
static PyMethodDef math_methods[] = {
{"acos", math_acos, METH_O, math_acos_doc},
{"asin", math_asin, METH_O, math_asin_doc},
@@ -358,6 +384,8 @@
{"fmod", math_fmod, METH_VARARGS, math_fmod_doc},
{"frexp", math_frexp, METH_O, math_frexp_doc},
{"hypot", math_hypot, METH_VARARGS, math_hypot_doc},
+ {"isinf", math_isinf, METH_O, math_isinf_doc},
+ {"isnan", math_isnan, METH_O, math_isnan_doc},
{"ldexp", math_ldexp, METH_VARARGS, math_ldexp_doc},
{"log", math_log, METH_VARARGS, math_log_doc},
{"log10", math_log10, METH_O, math_log10_doc},
@@ -389,13 +417,13 @@
if (d == NULL)
goto finally;
- if (!(v = PyFloat_FromDouble(atan(1.0) * 4.0)))
+ if (!(v = PyFloat_FromDouble(Py_MATH_PI)))
goto finally;
if (PyDict_SetItemString(d, "pi", v) < 0)
goto finally;
Py_DECREF(v);
- if (!(v = PyFloat_FromDouble(exp(1.0))))
+ if (!(v = PyFloat_FromDouble(Py_MATH_E)))
goto finally;
if (PyDict_SetItemString(d, "e", v) < 0)
goto finally;