Add the example1.py sage code.

diff --git a/doc/example1.py b/doc/example1.py
new file mode 100644 (file)
index 0000000..9dbe06f
--- /dev/null
+++ b/doc/example1.py
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+#!/home/mjo/bin/sage
+
+# example1.py
+#
+# In the paper, we display a lot of sage code to be entered at the
+# prompt. It's not much fun re-entering all of these formulas every
+# time you'd like to work on the paper, so a quick load('example1.py')
+# from the sage prompt will pull all of this stuff in for you.
+#
+
+x,y,z = var('x,y,z')
+
+f = 1 + x + x*y + x*y*z
+
+g = [[[ f(x=a, y=b, z=c) for a in range(0,3) ] for b in range(0,3) ] for c in range(0,3) ]
+
+def grid(x,y,z):
+    return g[z][y][x]
+
+def I(x,y,z):
+    return grid(x,y,z)
+
+def F(x,y,z):
+    return grid(x-1, y, z)
+
+def B(x,y,z):
+    return grid(x+1, y, z)
+
+def L(x,y,z):
+    return grid(x, y-1, z)
+
+def R(x,y,z):
+    return grid(x, y+1, z)
+
+def T(x,y,z): 
+    return grid(x, y, z+1)
+
+def D(x,y,z): 
+    return grid(x, y, z-1)
+
+def FL(x,y,z):
+    return grid(x-1, y-1, z)
+
+def FR(x,y,z):
+    return grid(x-1, y+1, z)
+
+def FD(x,y,z):
+    return grid(x-1, y, z-1)
+
+def FT(x,y,z):
+    return grid(x-1, y, z+1)
+
+def BL(x,y,z):
+    return grid(x+1, y-1, z)
+
+def BR(x,y,z):
+    return grid(x+1, y+1, z)
+
+def BD(x,y,z):
+    return grid(x+1, y, z-1)
+
+def BT(x,y,z):
+    return grid(x+1, y, z+1)
+
+def LD(x,y,z):
+    return grid(x, y-1, z-1)
+
+def LT(x,y,z): 
+    return grid(x, y-1, z+1)
+
+def RD(x,y,z): 
+    return grid(x, y+1, z-1)
+
+def RT(x,y,z): 
+    return grid(x, y+1, z+1)
+
+def FLD(x,y,z):
+    return grid(x-1, y-1, z-1)
+
+def FLT(x,y,z):
+    return grid(x-1, y-1, z+1)
+
+def FRD(x,y,z):
+    return grid(x-1, y+1, z-1)
+
+def FRT(x,y,z):
+    return grid(x-1, y+1, z+1)
+
+def BLD(x,y,z): 
+    return grid(x+1, y-1, z-1)
+
+def BLT(x,y,z):
+    return grid(x+1, y-1, z+1)
+
+def BRD(x,y,z):
+    return grid(x+1, y+1, z-1)
+
+def BRT(x,y,z):
+    return grid(x+1, y+1, z+1)
+