Ticket #1400: 1400-quadratic_field_order.patch

a/sage/rings/number_field/class_group.py

@@ -190 +190 @@
-        """
-        return self.parent()(self.__ideal.reduce_equiv())
-
-
-
-
-
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
-
-    def ideal(self):
-        """

a/sage/rings/number_field/number_field_ideal.py

@@ -1090 +1090 @@
-            return ZZ(self._pari_prime.getattr('f'))
-        raise ValueError, "the ideal (= %s) is not prime"%self
-
+    def order(self):
+        """
+        Return the (multiplicative) order of the fractional ideal self
+        viewed as an element of the underlying class group.
+
+        EXAMPLES:
+            sage: QF.<x> = QuadraticField(-39)
+            sage: QF.ideal(1+x).order()
+            1
+            sage: QF.ideal(2, 1/2*x - 1/2).order()
+            4
+        """
+        try:
+            return self.__order
+        except AttributeError:
+            k = 1
+            I = self.reduce_equiv()
+            J = I
+            while True:
+                if J.is_principal():
+                    self.__order = k
+                    return k
+                else:
+                    J = (J*I).reduce_equiv()
+                    k = k + 1
+
+    multiplicative_order = order
+
+
+
-def is_NumberFieldFractionalIdeal(x):
-    """
-    Return True if x is a fractional ideal of a number field.