import numpy legval rather than copy code

doc/changes.rst

@@ -5,7 +5,7 @@ specter change log
 0.8.6 (unreleased)
 ------------------
 
-* No changes yet.
+* Added numba-ized legval for ~20% overall ex2d speedup (PR #61).
 
 0.8.5 (2018-05-10)
 ------------------

py/specter/util/util.py

@@ -226,9 +226,8 @@ def outer(x, y, out):
         return np.multiply(x[:, None], y[None, :], out)
 
 
-#have faster numba version of legval if numba is available
+# have faster numba version of legval if numba is available
 try:
-    #this is the faster, flexible, most readable version
     if 'NUMBA_DISABLE_JIT' in os.environ:
         raise ImportError
     import numba
@@ -248,38 +247,9 @@ def legval_numba(x, c):
         return c0 + c1*x
 
 except ImportError:
-    #in the event there is no numba, revert to the orig legval
-    #this is an exact copy of numpy's legval
-    def legval_numba(x, c, tensor=True):
-        c = np.array(c, ndmin=1, copy=0)
-        if c.dtype.char in '?bBhHiIlLqQpP':
-            c = c.astype(np.double)
-        if isinstance(x, (tuple, list)):
-            x = np.asarray(x)
-        if isinstance(x, np.ndarray) and tensor:
-            c = c.reshape(c.shape + (1,)*x.ndim)
-
-        if len(c) == 1:
-            c0 = c[0]
-            c1 = 0
-        elif len(c) == 2:
-            c0 = c[0]
-            c1 = c[1]
-        else:
-            nd = len(c)
-            c0 = c[-2]
-            c1 = c[-1]
-            for i in range(3, len(c) + 1):
-                tmp = c0
-                nd = nd - 1
-                c0 = c[-i] - (c1*(nd - 1))/nd
-                c1 = tmp + (c1*x*(2*nd - 1))/nd
-        return c0 + c1*x
-
-
-
-
-
+    # in the event there is no numba, revert to the orig legval while
+    # still calling it legval_numba so that they can be used interchangeably
+    from numpy.polynomial.legendre import legval as legval_numba