Add StochasticOdd, another sweep on text.

Author: awf

docs/source/05-stochastic-rounding.ipynb

@@ -113,6 +113,15 @@ def round_float(
                     (d - floord > 0.5) or ((d - floord == 0.5) and _isodd(floord))
                 )
 
+                should_round_away = d > srbits
+            case RoundMode.StochasticOdd:
+                ## RTNE delta to srbits
+                d = delta * 2.0**srnumbits
+                floord = np.floor(d).astype(np.int64)
+                d = floord + (
+                    (d - floord > 0.5) or ((d - floord == 0.5) and ~_isodd(floord))
+                )
+
                 should_round_away = d > srbits
             case RoundMode.StochasticFastest:
                 should_round_away = delta > (0.5 + srbits) * 2.0**-srnumbits

src/gfloat/round.py

@@ -94,6 +94,15 @@ def round_ndarray(
             dd = d - floord
             drnd = floord + (dd > 0.5) + ((dd == 0.5) & _isodd(floord))
 
+            should_round_away = drnd > srbits
+        case RoundMode.StochasticOdd:
+            assert srbits is not None
+            ## RTNO delta to srbits
+            d = delta * 2.0**srnumbits
+            floord = np.floor(d).astype(np.int64)
+            dd = d - floord
+            drnd = floord + (dd > 0.5) + ((dd == 0.5) & ~_isodd(floord))
+
             should_round_away = drnd > srbits
         case RoundMode.StochasticFast:
             assert srbits is not None

src/gfloat/round_ndarray.py

@@ -19,6 +19,7 @@ class RoundMode(Enum):
     Stochastic = 6  #: Stochastic rounding
     StochasticFast = 7  #: Stochastic rounding - faster, but biased, see [Note 1].
     StochasticFastest = 8  #: Stochastic rounding - incorrect, see [Note 1].
+    StochasticOdd = 9  #: Stochastic rounding, RTNO before comparison
 
 
 # [Note 1]:

src/gfloat/types.py

@@ -541,7 +541,7 @@ def test_stochastic_rounding(
     np.testing.assert_allclose(count_v1, expected_up_count, atol=atol)
 
 
-def test_stochastic_rounding_2() -> None:
+def test_stochastic_rounding_scalar_eq_array() -> None:
     fi = format_info_p3109(3)
 
     v0 = decode_ndarray(fi, np.arange(255))