Update all doctests to use index[] notation instead of __call__.

diff --git a/mjo/symbol_sequence.py b/mjo/symbol_sequence.py
index 7f6c9db7622a2e360a964dfda7cd721c01f885f9..a6459304e2ddb7a660395473250b16fa7d9e2855 100644 (file)
--- a/mjo/symbol_sequence.py
+++ b/mjo/symbol_sequence.py
@@ -2,12 +2,13 @@ from sage.all import *
 
 class SymbolSequence:
     """
-    A callable object which imitates a function from ZZ^n to a
-    sequence with n subscripts.
+    An iterable object which acts like a sequence of symbolic
+    expressions (variables).
 
     INPUT:
 
-      - ``name`` -- The sequence name.
+      - ``name`` -- The sequence name. For example, if you name the
+        sequence `x`, the variables will be called `x0`, `x1`,...
 
       - ``latex_name`` -- An optional latex expression (string) to
         use instead of `name` when converting the symbols to latex.
@@ -17,80 +18,63 @@ class SymbolSequence:
 
     OUTPUT:
 
-    A callable object returning symbolic expressions.
+    An iterable object containing symbolic expressions.
 
     EXAMPLES:
 
+    The simplest use case::
+
+        sage: a = SymbolSequence('a')
+        sage: a[0]
+        a0
+        sage: a[1]
+        a1
+
     Create coefficients for polynomials of arbitrary degree::
 
         sage: a = SymbolSequence('a')
-        sage: p = sum([ a(i)*x^i for i in range(0,5)])
+        sage: p = sum([ a[i]*x^i for i in range(0,5)])
         sage: p
         a4*x^4 + a3*x^3 + a2*x^2 + a1*x + a0
 
     Using a different latex name since 'lambda' is reserved::
 
         sage: l = SymbolSequence('l', '\lambda')
-        sage: l(0)
+        sage: l[0]
         l0
-        sage: latex(l(0))
+        sage: latex(l[0])
         \lambda_{0}
 
     Using multiple indices::
 
         sage: a = SymbolSequence('a')
-        sage: a(0,1,2)
+        sage: a[0,1,2]
         a012
-        sage: latex(a(0,1,2))
+        sage: latex(a[0,1,2])
         a_{0}_{1}_{2}
-        sage: [ a(i,j) for i in range(0,2) for j in range(0,2) ]
+        sage: [ a[i,j] for i in range(0,2) for j in range(0,2) ]
         [a00, a01, a10, a11]
 
-    If no index is given, an unsubscripted symbol is returned::
-
-        sage: a = SymbolSequence('a')
-        sage: a()
-        a
-
     You can pass slice objects instead of integers to obtain a list of
     symbols::
 
         sage: a = SymbolSequence('a')
-        sage: a(slice(5,7))
+        sage: a[5:7]
         [a5, a6]
 
     This even works for the second, third, etc. indices::
 
         sage: a = SymbolSequence('a')
-        sage: a(slice(0,2), slice(0,2))
+        sage: a[0:2, 0:2]
         [a00, a01, a10, a11]
 
-    You can also index with the list index operator::
-
-        sage: a = SymbolSequence('a')
-        sage: a[1]
-        a1
-
-    This allows you to retrieve one-dimensional slices easily::
-
-        sage: a = SymbolSequence('a')
-        sage: a[0:5]
-        [a0, a1, a2, a3, a4]
-
-    If for whatever reason you prefer square brackets, the following
-    also works::
-
-        sage: a = SymbolSequence('a')
-        sage: a[1,3]
-        a13
-
     TESTS:
 
     We shouldn't overwrite variables in the global namespace::
 
         sage: a = SymbolSequence('a')
         sage: a0 = 4
-        sage: a(0)
+        sage: a[0]
         a0
         sage: a0
         4
@@ -100,16 +84,16 @@ class SymbolSequence:
     representation and compare because the output is unpredictable::
 
         sage: a = SymbolSequence()
-        sage: a0str = str(a(0))
+        sage: a0str = str(a[0])
         sage: str(a(0)) == a0str
         True
 
     Slices and single indices work when combined::
 
         sage: a = SymbolSequence('a')
-        sage: a(3, slice(0,2))
+        sage: a[3, 0:2]
         [a30, a31]
-        sage: a(slice(0,2), 3)
+        sage: a[0:2, 3]
         [a03, a13]
 
     """