Merge pull request numpy#3895 from larsmans/norm-dot

ENH: use dot in linalg.norm

Author: charris

numpy/linalg/linalg.py

@@ -2053,7 +2053,12 @@ def norm(x, ord=None, axis=None):
 
     # Check the default case first and handle it immediately.
     if ord is None and axis is None:
-        return sqrt(add.reduce((x.conj() * x).real, axis=None))
+        x = x.ravel(order='K')
+        if isComplexType(x.dtype.type):
+            sqnorm = dot(x.real, x.real) + dot(x.imag, x.imag)
+        else:
+            sqnorm = dot(x, x)
+        return sqrt(sqnorm)
 
     # Normalize the `axis` argument to a tuple.
     nd = x.ndim