add "e" and "pi" aliases to libc.math declarations to bring it closer to a...

add "e" and "pi" aliases to libc.math declarations to bring it closer to a drop-in replacement for Python's math module

CHANGES.rst

@@ -24,6 +24,9 @@ Features added
 
 * for-loop iteration over "std::string".
 
+* ``libc/math.pxd`` provides ``e`` and ``pi`` as alias constants to simplify
+  usage as a drop-in replacement for Python's math module.
+
 Bugs fixed
 ----------
 

Cython/Includes/libc/math.pxd

 cdef extern from "math.h" nogil:
     double M_E
+    double e "M_E"  # as in Python's math module
     double M_LOG2E
     double M_LOG10E
     double M_LN2
     double M_LN10
     double M_PI
+    double pi "M_PI"  # as in Python's math module
     double M_PI_2
     double M_PI_4
     double M_1_PI
@@ -16,6 +18,7 @@ cdef extern from "math.h" nogil:
     # C99 constants
     float INFINITY
     float NAN
+    # note: not providing "nan" and "inf" aliases here as nan() is a function in C
     double HUGE_VAL
     float HUGE_VALF
     long double HUGE_VALL

tests/compile/libc_math.pyx → tests/run/libc_math.pyx

+# mode: run
+
 from libc.math cimport (M_E, M_LOG2E, M_LOG10E, M_LN2, M_LN10, M_PI, M_PI_2,
         M_PI_4, M_1_PI, M_2_PI, M_2_SQRTPI, M_SQRT2, M_SQRT1_2)
 from libc.math cimport (acos, asin, atan, atan2, cos, sin, tan, cosh, sinh,
         tanh, acosh, asinh, atanh, exp, log, log10, pow, sqrt)
+cimport libc.math as libc_math
+
 
 def test_pi():
     """
@@ -11,6 +15,16 @@ def test_pi():
     """
     return M_PI
 
+
+def test_renamed_constants(math):
+    """
+    >>> import math
+    >>> test_renamed_constants(math)
+    """
+    assert libc_math.M_E == libc_math.e == math.e
+    assert libc_math.M_PI == libc_math.pi == math.pi
+
+
 def test_sin(x):
     """
     >>> test_sin(0)