Ticket #10052: trac_10052-steenrod.delta3to4.patch

sage/algebras/steenrod/steenrod_algebra_misc.py

@@ -246 +246 @@
         # p odd:
         e = list(profile[0]) + [truncation_type]*len(profile[0])
         k = list(profile[1])
+        if not set(k).issubset(set([1,2])):
+            return False
         if truncation_type > 0:
             k = k + [2]
         else:
@@ -391 +393 @@
         sage: normalize_profile(([2,1], [2,2,2]), precision=84, p=13)
         (((2, 1), (2, 2, 2)), 0)
         sage: normalize_profile((lambda n: 0, lambda n: 2), precision=4, p=11)
-        (((0, 0, 0), (2, 2, 2)), +Infinity)
+        (((0, 0, 0), ()), +Infinity)
 
     As at the prime 2, negative numbers in the first component are
-    converted to zeroes.  Numbers in the second component are forced
-    to lie between 1 and 2: numbers larger than 2 get converted to 2,
-    etc. ::
+    converted to zeroes.  Numbers in the second component must be
+    either 1 and 2, or else an error is raised::
 
-        sage: normalize_profile((lambda n: -n, lambda n: 2+n), precision=4, p=11)
-        (((0, 0, 0), (2, 2, 2)), +Infinity)
+        sage: normalize_profile((lambda n: -n, lambda n: 1), precision=4, p=11)
+        (((0, 0, 0), (1, 1, 1)), +Infinity)
+        sage: normalize_profile([[0,0,0], [1,2,3,2,1]], p=11)
+        Traceback (most recent call last):
+        ...
+        ValueError: Invalid profile
     """
     from inspect import isfunction
     from sage.rings.infinity import Infinity
@@ -488 +493 @@
                 k = tuple(k)
             elif isfunction(k):
                 # k is a function: turn it into a tuple.
-                k = [max(1, min(2, k(i))) for i in range(precision-1)]
-                k = tuple(k)
+                k = tuple([k(i) for i in range(precision-1)])
+            # Remove trailing ones from k if truncation_type is 'zero',
+            # remove trailing twos if truncation_type is 'Infinity'.
+            if truncation_type == 0:
+                while len(k) > 0 and k[-1] == 1:
+                    k = k[:-1]
+            else:
+                while len(k) > 0 and k[-1] == 2:
+                    k = k[:-1]
             new_profile = (e, k)
         if is_valid_profile(new_profile, truncation_type, p):
             return new_profile, truncation_type