Merge pull request #280 from curveresearch/fix-calc-diff

Fix calc diff
curveresearch · Nov 5, 2023 · d82882a · d82882a
2 parents 71c5518 + 06df807
commit d82882a
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Showing 3 changed files with 19 additions and 5 deletions.
diff --git a/changelog.d/20231103_115610_chanhosuh_fix_calc_diff.rst b/changelog.d/20231103_115610_chanhosuh_fix_calc_diff.rst
@@ -0,0 +1,4 @@
+Fixed
+-----
+
+- Fixed handling of integer signed division in Tricrypto-NG's `get_y` calc.
diff --git a/curvesim/pool/cryptoswap/calcs/tricrypto_ng.py b/curvesim/pool/cryptoswap/calcs/tricrypto_ng.py
@@ -101,6 +101,7 @@ def get_y(  # noqa: complexity: 18
     else:
         _c = gamma2 * _c_neg // D * ANN // 27 // A_MULTIPLIER
     c += _c
+    c_is_neg = c < 0
 
     # (10**18 + gamma)**2/27
     d: int = (10**18 + gamma) ** 2 // 27
@@ -131,6 +132,8 @@ def get_y(  # noqa: complexity: 18
     additional_prec: int = 0
     if b_is_neg:
         b *= -1
+    if c_is_neg:
+        c *= -1
     if abs(a) > abs(b):
         additional_prec = abs(a // b)
         a = a * additional_prec // divider
@@ -145,19 +148,25 @@ def get_y(  # noqa: complexity: 18
         d = d // additional_prec // divider
     if b_is_neg:
         b *= -1
+    if c_is_neg:
+        c *= -1
 
     # 3*a*c/b - b
-    _3ac: int = 3 * a * c
-    if b_is_neg:
+    _3ac: int = (3 * a) * c
+    if sign(_3ac) != sign(b):
         delta0: int = -(_3ac // -b) - b
     else:
         delta0 = _3ac // b - b
 
     # 9*a*c/b - 2*b - 27*a**2/b*d/b
+    if sign(_3ac) != sign(b):
+        delta1: int = -(3 * _3ac // -b) - 2 * b
+    else:
+        delta1 = 3 * _3ac // b - 2 * b
     if b_is_neg:
-        delta1: int = -(3 * _3ac // -b) - 2 * b - 27 * a**2 // -b * d // -b
+        delta1 -= 27 * a**2 // -b * d // -b
     else:
-        delta1 = 3 * _3ac // b - 2 * b - 27 * a**2 // b * d // b
+        delta1 -= 27 * a**2 // b * d // b
 
     # delta1**2 + 4*delta0**2/b*delta0
     if b_is_neg:

diff --git a/test/unit/test_tricrypto.py b/test/unit/test_tricrypto.py
@@ -20,6 +20,7 @@
     _newton_y,
     wad_exp,
 )
+
 from ..fixtures.pool import pack_prices, unpack_prices
 
 
@@ -305,7 +306,7 @@ def test_get_p(tricrypto_math, A, gamma, x0, x1, x2):
         st.integers(min_value=0, max_value=2),
         st.integers(min_value=0, max_value=2),
     ).filter(lambda x: x[0] != x[1]),
-    st.integers(min_value=1, max_value=10000),
+    st.integers(min_value=1, max_value=5500),
 )
 @settings(
     suppress_health_check=[HealthCheck.function_scoped_fixture],