Ticket #11685: trac_11685_pari_zero_list.patch

sage/rings/finite_rings/element_ext_pari.py

@@ -105 +105 @@
             sage: pari(x)
             Mod(Mod(1, 3)*a^3 + Mod(2, 3)*a^2 + Mod(1, 3), Mod(1, 3)*a^11 + Mod(2, 3)*a^2 + Mod(1, 3))
 
+        As well as #11685::
+            
+            sage: K.<a> = GF(3^11)
+            sage: K([0])
+            0
+            sage: K([0]) == 0
+            True
+
         If the list is longer than the degree, we just get the result
         modulo the modulus::
 
@@ -162 +170 @@
                 # multiply it with _pari_one (which equals Mod(1,p)) to
                 # fix the characteristic and then mod out by the modulus.
                 # See #10486.
-                self.__value = (pari(value).Polrev("a") * parent._pari_one()).Mod(parent._pari_modulus())
+                value = pari(value)
+                if value:
+                    value = value.Polrev("a")
+                else:
+                    value = pari(0)
+                self.__value = (value * parent._pari_one()).Mod(parent._pari_modulus()) 
             else:
                 try:
                     self.__value = pari(value).Mod(parent._pari_modulus())*parent._pari_one()