Ticket #2853: 2853.1.patch

sage/combinat/crystals/letters.py

@@ -142 +142 @@
         """
         return self._digraph
     
-
     def __contains__(self, x):
         """
         EXAMPLES:
@@ -287 +286 @@
 
         sage: C.check()
         True
-    """
+
+    """
+    
+    def weight(self):
+        """
+        Returns the weight of self.
+
+        EXAMPLES:
+            sage: [v.weight() for v in CrystalOfLetters(['A',3])]
+            [(1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, 0, 0, 1)]
+        """
+        return self._parent.weight_lattice_realization()._term(self.value-1)
+
     def e(self, i):
         r"""
         Returns the action of $e_i$ on self.
@@ -331 +342 @@
         sage: C.check()
         True
     """
+    
+    def weight(self):
+        """
+        Returns the weight of self.
+
+        EXAMPLES:
+            sage: [v.weight() for v in CrystalOfLetters(['B',3])]
+            [(1, 0, 0),
+             (0, 1, 0),
+             (0, 0, 1),
+             (0, 0, 0),
+             (0, 0, -1),
+             (0, -1, 0),
+             (-1, 0, 0)]
+        """
+        if self.value > 0:
+            return self._parent.weight_lattice_realization()._term(self.value-1)
+        elif self.value < 0:
+            return -self._parent.weight_lattice_realization()._term(-self.value-1)
+        else:
+            return self._parent.weight_lattice_realization()._free_module(0)
+
     def e(self, i):
         r"""
         Returns the action of $e_i$ on self.
@@ -410 +443 @@
          [False, False, False, False, False, False]]
         sage: C.check()
         True
-   
-    """
+    """
+    
+    def weight(self):
+        """
+        Returns the weight of self.
+
+        EXAMPLES:
+            sage: [v.weight() for v in CrystalOfLetters(['C',3])]
+            [(1, 0, 0), (0, 1, 0), (0, 0, 1), (0, 0, -1), (0, -1, 0), (-1, 0, 0)]
+        
+        """
+        if self.value > 0:
+            return self._parent.weight_lattice_realization()._term(self.value-1)
+        elif self.value < 0:
+            return -self._parent.weight_lattice_realization()._term(-self.value-1)
+        else:
+            return self._parent.weight_lattice_realization()._free_module(0)
+
     def e(self, i):
         r"""
         Returns the action of $e_i$ on self.
@@ -472 +521 @@
         [1, 2, 3, 4, -4, -3, -2, -1]
         sage: C.check()
         True
-    """
+        
+    """
+
+    def weight(self):
+        """
+        Returns the weight of self.
+
+        EXAMPLES:
+            sage: [v.weight() for v in CrystalOfLetters(['D',4])]
+            [(1, 0, 0, 0),
+             (0, 1, 0, 0),
+             (0, 0, 1, 0),
+             (0, 0, 0, 1),
+             (0, 0, 0, -1),
+             (0, 0, -1, 0),
+             (0, -1, 0, 0),
+             (-1, 0, 0, 0)]
+        """
+        if self.value > 0:
+            return self._parent.weight_lattice_realization()._term(self.value-1)
+        elif self.value < 0:
+            return -self._parent.weight_lattice_realization()._term(-self.value-1)
+        else:
+            return self._parent.weight_lattice_realization()._free_module(0)
+
     def e(self, i):
         r"""
         Returns the action of $e_i$ on self.
@@ -552 +625 @@
         sage: C.check()
         True
     """
+    
+    def weight(self):
+        """
+        Returns the weight of self.
+
+        EXAMPLES:
+            sage: [v.weight() for v in CrystalOfLetters(['G',2])]
+            [(1, 0, -1), (1, -1, 0), (0, 1, -1), (0, 0, 0), (0, -1, 1), (-1, 1, 0), (-1, 0, 1)]
+        """
+        if self.value == 1:
+            return self._parent.weight_lattice_realization()._free_module((1, 0, -1))
+        elif self.value == 2:
+            return self._parent.weight_lattice_realization()._free_module((1, -1, 0))
+        elif self.value == 3:
+            return self._parent.weight_lattice_realization()._free_module((0, 1, -1))
+        elif self.value == 0:
+            return self._parent.weight_lattice_realization()._free_module((0, 0, 0))
+        elif self.value == -3:
+            return self._parent.weight_lattice_realization()._free_module((0, -1, 1))
+        elif self.value == -2:
+            return self._parent.weight_lattice_realization()._free_module((-1, 1, 0))
+        elif self.value == -1:
+            return self._parent.weight_lattice_realization()._free_module((-1, 0, 1))
+        else:
+            raise RuntimeError, "G2 crystal of letters element %d not valid"%self.value
+
     def e(self, i):
         r"""
         Returns the action of $e_i$ on self.

sage/combinat/crystals/tensor_product.py

@@ -235 +235 @@
             else:
                 self.module_generators = [ self(*x) for x in options['generators']]
 
-
     def __call__(self, *args):
         """
         EXAMPLES:
@@ -272 +271 @@
         k = position[0]
         return self.set_index(k, self[k].e(i))
     
+    def weight(self):
+        """
+        Returns the weight of self.
+
+        EXAMPLES:
+            sage: C = CrystalOfLetters(['A',3])
+            sage: T = TensorProductOfCrystals(C,C)
+            sage: T(C(1),C(2)).weight()
+            (1, 1, 0, 0)
+        """
+        return sum(self[j].weight() for j in range(len(self)))
+
     def f(self, i):
         """
         Returns the action of $f_i$ on self.