Fix omega() method

Author: jdemeyer

cypari2/gen.pyx

@@ -3403,7 +3403,7 @@ cdef class Gen(Gen_base):
         sig_on()
         return new_gen(elltors(self.g))
 
-    def omega(self, unsigned long precision=0):
+    def omega(self):
         """
         Return the basis for the period lattice of this elliptic curve.
 
@@ -3415,9 +3415,21 @@ cdef class Gen(Gen_base):
         >>> e = pari([0, -1, 1, -10, -20]).ellinit()
         >>> e.omega()
         [1.26920930427955, 0.634604652139777 - 1.45881661693850*I]
+
+        The precision is determined by the ``ellinit`` call::
+
+        >>> e = pari([0, -1, 1, -10, -20]).ellinit(precision=256)
+        >>> e.omega().bitprecision()
+        256
+
+        This also works over quadratic imaginary number fields::
+
+        >>> e = pari.ellinit([0, -1, 1, -10, -20], "nfinit(y^2 - 2)")
+        >>> if pari.version() >= (2, 10, 1):
+        ...     w = e.omega()
         """
         sig_on()
-        return new_gen(ellR_omega(self.g, prec_bits_to_words(precision)))
+        return new_gen(member_omega(self.g))
 
     def disc(self):
         """