minor performance improvements for philox

modules/rng_philox.py

@@ -26,7 +26,7 @@ two_pow32_inv_2pi = np.array([2.3283064e-10 * 6.2831855], dtype=np.float32)
 
 def uint32(x):
     """Converts (N,) np.uint64 array into (2, N) np.unit32 array."""
-    return np.moveaxis(x.view(np.uint32).reshape(-1, 2), 0, 1)
+    return x.view(np.uint32).reshape(-1, 2).transpose(1, 0)
 
 
 def philox4_round(counter, key):
@@ -65,8 +65,8 @@ def philox4_32(counter, key, rounds=10):
 
 def box_muller(x, y):
     """Returns just the first out of two numbers generated by Box–Muller transform algorithm."""
-    u = x.astype(np.float32) * two_pow32_inv + two_pow32_inv / 2
-    v = y.astype(np.float32) * two_pow32_inv_2pi + two_pow32_inv_2pi / 2
+    u = x * two_pow32_inv + two_pow32_inv / 2
+    v = y * two_pow32_inv_2pi + two_pow32_inv_2pi / 2
 
     s = np.sqrt(-2.0 * np.log(u))
 
@@ -93,7 +93,9 @@ class Generator:
         counter[2] = np.arange(n, dtype=np.uint32)  # up to 2^32 numbers can be generated - if you want more you'd need to spill into counter[3]
         self.offset += 1
 
-        key = uint32(np.array([[self.seed] * n], dtype=np.uint64))
+        key = np.empty(n, dtype=np.uint64)
+        key.fill(self.seed)
+        key = uint32(key)
 
         g = philox4_32(counter, key)