Changeset 7609:e38650e27e86

Timestamp:

11/28/07 10:28:15 (5 years ago)

Author:

Robert Bradshaw <robertwb@…>

Branch:

default

Message:

Use long longs instead of Integers for small order calculations

File:

• sage/groups/perm_gps/permgroup_element.pyx (modified) (3 diffs)

sage/groups/perm_gps/permgroup_element.pyx

@@ -69 +69 @@
 from sage.rings.integer import Integer
 
+from sage.ext.arith cimport arith_llong
+cdef arith_llong arith = arith_llong()
+cdef extern from *:
+    long long LONG_LONG_MAX
+
 #import permgroup_named
 
@@ -530 +535 @@
             sage: s.order()
             6
-        """
-        order = Integer(1)
+            
+        TESTS: 
+            sage: prod(primes(150))
+            1492182350939279320058875736615841068547583863326864530410
+            sage: L = [tuple(range(sum(primes(p))+1, sum(primes(p))+1+p)) for p in primes(150)]
+            sage: PermutationGroupElement(L).order()
+            1492182350939279320058875736615841068547583863326864530410
+        """
+        order = None
+        cdef long long order_c = 1
         cdef int cycle_len
         cdef int i, k
@@ -545 +558 @@
                 k = self.perm[k]
                 cycle_len += 1
-            order = order.lcm(cycle_len)
+            if order is not None:
+                order = order.lcm(cycle_len)
+            else:
+                order_c = (order_c * cycle_len) / arith.c_gcd_longlong(order_c, cycle_len)
+                if order_c > LONG_LONG_MAX / (self.n - i):
+                    order = Integer(order_c)
         sage_free(seen)
-        return order
+        return int(order_c) if order is None else order
         
     def sign(self):