Fix Expression.__hash__

[linpy.git] / pypol / linear.py

diff --git a/pypol/linear.py b/pypol/linear.py
index bd7037b..2c71c02 100644 (file)
--- a/pypol/linear.py
+++ b/pypol/linear.py
@@ -62,7 +62,7 @@ class Expression:
                 for symbol, coefficient in coefficients if coefficient != 0]
         if len(coefficients) == 0:
             return Constant(constant)
-        elif len(coefficients) == 1:
+        elif len(coefficients) == 1 and constant == 0:
             symbol, coefficient = coefficients[0]
             if coefficient == 1:
                 return Symbol(symbol)
@@ -271,7 +271,7 @@ class Expression:
                 self.constant == other.constant
 
     def __hash__(self):
-        return hash((self._coefficients, self._constant))
+        return hash((tuple(sorted(self._coefficients.items())), self._constant))
 
     def _toint(self):
         lcm = functools.reduce(lambda a, b: a*b // gcd(a, b),