Add comparison to "SRFast"

Author: awf

docs/source/05-stochastic-rounding.ipynb

@@ -106,6 +106,8 @@ def round_float(
             should_round_away = delta > 0.5 or (delta == 0.5 and code_is_odd)
         if rnd == RoundMode.Stochastic:
             should_round_away = delta > (0.5 + srbits) * 2.0**-srnumbits
+        if rnd == RoundMode.StochasticFast:
+            should_round_away = delta > srbits * 2.0**-srnumbits
 
         if should_round_away:
             # This may increase isignificand to 2**p,

src/gfloat/round.py

@@ -17,6 +17,7 @@ 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 - possibly faster, but biased.
 
 
 class FloatClass(Enum):