diff --git a/code/code_gen/calc.py b/code/code_gen/calc.py
new file mode 100644
index 0000000..f893bc0
--- /dev/null
+++ b/code/code_gen/calc.py
@@ -0,0 +1,125 @@
+#
+# This example shows how to write a basic calculator with variables.
+#
+
+from lark import Lark, Transformer, v_args
+
+
+try:
+    input = raw_input   # For Python2 compatibility
+except NameError:
+    pass
+
+'''
+    ?function: "log" -> log
+             | "exp" -> exp
+             | "dx"  -> dx
+             | "d2x" -> d2x
+
+    '''
+
+
+calc_grammar = """
+    ?varlist: "[" [NAME ("," NAME)*] "]"
+
+    ?start: NAME "=" sum    -> assign_var
+          | varlist
+
+    ?sum: product
+        | sum "+" product   -> add
+        | sum "-" product   -> sub
+
+    ?product: atom
+        | product "*" atom  -> mul
+        | product "/" atom  -> div
+
+    ?atom: NUMBER           -> number
+         | "-" atom         -> neg
+         | NAME             -> var
+         | "(" sum ")"
+         | function "(" sum ")" -> fcall
+
+    ?function: "log" -> log
+             | "exp" -> exp
+             | "dx"  -> dx
+             | "d2x" -> d2x
+             | "sqrt" -> sqrt
+
+    %import common.CNAME -> NAME
+    %import common.NUMBER
+    %import common.WS
+
+    %ignore WS
+"""
+
+
+@v_args(inline=True)    # Affects the signatures of the methods
+class CalculateTree(Transformer):
+    from operator import add, sub, mul, truediv as div, neg
+    number = float
+
+    def __init__(self):
+        self.primary = []
+        self.derived = {}
+
+    def varlist(self, *args):
+        for arg in args:
+            self.primary.append(arg.value)
+        return self.primary
+
+    def assign_var(self, name, value):
+        self.derived[name] = value
+        return "{} = {}".format(name, value)
+
+    def var(self, name):
+        return name
+
+    def fcall (self, a, b):
+        return "( {} ( {} ) )".format(a, b)
+
+    def neg(self, value):
+        return "( - {} )".format(value)
+
+    def add(self, a, b):
+        return "( {} + {} )".format(a, b)
+
+    def sub(self, a, b):
+        return "( {} - {} )".format(a, b)
+
+    def mul(self, a, b):
+        return "( {} * {} )".format(a, b)
+
+    def div(self, a, b):
+        return "( {} / {} )".format(a, b)
+
+    log = lambda self : "log"
+    exp = lambda self : "exp"
+    dx  = lambda self : "dx"
+    d2x = lambda self : "d2x"
+    sqrt = lambda self : "sqrt"
+
+tf=CalculateTree()
+
+calc_parser = Lark(calc_grammar, parser='lalr' , transformer=tf)
+calc = calc_parser.parse
+
+
+def main():
+    while True:
+        try:
+            s = input('> ')
+        except EOFError:
+            break
+        print(calc(s))
+
+
+def test():
+    with open("terms.input") as inputfile:
+        for line in inputfile:
+             if len(line.strip()) > 0:
+                 print(calc(line))
+
+
+if __name__ == '__main__':
+    test()
+    # main()
diff --git a/code/code_gen/code_gen.py b/code/code_gen/code_gen.py
new file mode 100644
index 0000000..f893bc0
--- /dev/null
+++ b/code/code_gen/code_gen.py
@@ -0,0 +1,125 @@
+#
+# This example shows how to write a basic calculator with variables.
+#
+
+from lark import Lark, Transformer, v_args
+
+
+try:
+    input = raw_input   # For Python2 compatibility
+except NameError:
+    pass
+
+'''
+    ?function: "log" -> log
+             | "exp" -> exp
+             | "dx"  -> dx
+             | "d2x" -> d2x
+
+    '''
+
+
+calc_grammar = """
+    ?varlist: "[" [NAME ("," NAME)*] "]"
+
+    ?start: NAME "=" sum    -> assign_var
+          | varlist
+
+    ?sum: product
+        | sum "+" product   -> add
+        | sum "-" product   -> sub
+
+    ?product: atom
+        | product "*" atom  -> mul
+        | product "/" atom  -> div
+
+    ?atom: NUMBER           -> number
+         | "-" atom         -> neg
+         | NAME             -> var
+         | "(" sum ")"
+         | function "(" sum ")" -> fcall
+
+    ?function: "log" -> log
+             | "exp" -> exp
+             | "dx"  -> dx
+             | "d2x" -> d2x
+             | "sqrt" -> sqrt
+
+    %import common.CNAME -> NAME
+    %import common.NUMBER
+    %import common.WS
+
+    %ignore WS
+"""
+
+
+@v_args(inline=True)    # Affects the signatures of the methods
+class CalculateTree(Transformer):
+    from operator import add, sub, mul, truediv as div, neg
+    number = float
+
+    def __init__(self):
+        self.primary = []
+        self.derived = {}
+
+    def varlist(self, *args):
+        for arg in args:
+            self.primary.append(arg.value)
+        return self.primary
+
+    def assign_var(self, name, value):
+        self.derived[name] = value
+        return "{} = {}".format(name, value)
+
+    def var(self, name):
+        return name
+
+    def fcall (self, a, b):
+        return "( {} ( {} ) )".format(a, b)
+
+    def neg(self, value):
+        return "( - {} )".format(value)
+
+    def add(self, a, b):
+        return "( {} + {} )".format(a, b)
+
+    def sub(self, a, b):
+        return "( {} - {} )".format(a, b)
+
+    def mul(self, a, b):
+        return "( {} * {} )".format(a, b)
+
+    def div(self, a, b):
+        return "( {} / {} )".format(a, b)
+
+    log = lambda self : "log"
+    exp = lambda self : "exp"
+    dx  = lambda self : "dx"
+    d2x = lambda self : "d2x"
+    sqrt = lambda self : "sqrt"
+
+tf=CalculateTree()
+
+calc_parser = Lark(calc_grammar, parser='lalr' , transformer=tf)
+calc = calc_parser.parse
+
+
+def main():
+    while True:
+        try:
+            s = input('> ')
+        except EOFError:
+            break
+        print(calc(s))
+
+
+def test():
+    with open("terms.input") as inputfile:
+        for line in inputfile:
+             if len(line.strip()) > 0:
+                 print(calc(line))
+
+
+if __name__ == '__main__':
+    test()
+    # main()
diff --git a/code/code_gen/terms.input b/code/code_gen/terms.input
new file mode 100644
index 0000000..560848e
--- /dev/null
+++ b/code/code_gen/terms.input
@@ -0,0 +1,5 @@
+[u, v, w, y]
+
+c = 1 - y
+wrate = 21000 * (1 - c) * exp (- 26.7 / (1 + 3 * c))
+dcdx = dx (y)