Rename rounding modes

Author: awf

src/gfloat/round.py

@@ -114,7 +114,7 @@ def round_float(
                 )
 
                 should_round_away = d > srbits
-            case RoundMode.StochasticNearly:
+            case RoundMode.StochasticFastest:
                 should_round_away = delta > (0.5 + srbits) * 2.0**-srnumbits
             case RoundMode.StochasticFast:
                 should_round_away = delta > srbits * 2.0**-srnumbits

src/gfloat/round_ndarray.py

@@ -95,11 +95,11 @@ def round_ndarray(
 
             should_round_away = d > srbits
         case RoundMode.StochasticFast:
-            assert srbits is not None
-            should_round_away = delta > srbits * 2.0**-srnumbits
-        case RoundMode.StochasticNearly:
             assert srbits is not None
             should_round_away = delta > (2 * srbits + 1) * 2.0 ** -(1 + srnumbits)
+        case RoundMode.StochasticFastest:
+            assert srbits is not None
+            should_round_away = delta > srbits * 2.0**-srnumbits
 
     isignificand = np.where(should_round_away, isignificand + 1, isignificand)
 

src/gfloat/types.py

@@ -17,14 +17,20 @@ class RoundMode(Enum):
     TiesToEven = 4  #: Round to nearest, ties to even
     TiesToAway = 5  #: Round to nearest, ties away from zero
     Stochastic = 6  #: Stochastic rounding
-    StochasticFast = 7  #: Stochastic rounding - faster, but biased.
-    StochasticNearly = 8  #: Stochastic rounding - incorrect, see [Note 1].
+    StochasticFast = 7  #: Stochastic rounding - faster, but biased, see [Note 1].
+    StochasticFastest = 8  #: Stochastic rounding - incorrect, see [Note 1].
 
 
 # [Note 1]:
-# StochasticNearly implements a stochastic rounding scheme that is unbiased in
+# StochasticFast implements a stochastic rounding scheme that is unbiased in
 # infinite precision, but biased when the quantity to be rounded is computed to
 # a finite precision.
+#
+# StochasticFastest implements a stochastic rounding scheme that is biased
+# (the rounded value is on average farther from zero than the true value).
+#
+# With a lot of SRbits (say 8 or more), these biases are negligible, and there
+# may be some efficiency advantage in using StochasticFast or StochasticFastest.
 
 
 class FloatClass(Enum):