diff --git a/pysd/__init__.py b/pysd/__init__.py
index 4666c714..545eb310 100644
--- a/pysd/__init__.py
+++ b/pysd/__init__.py
@@ -1,4 +1,5 @@
 from .pysd import read_vensim, read_xmile, load
+from . import py_backend
 from .py_backend import functions
 from .py_backend import utils
 from ._version import __version__
diff --git a/pysd/py_backend/functions.py b/pysd/py_backend/functions.py
index e62acf57..bef4ad59 100644
--- a/pysd/py_backend/functions.py
+++ b/pysd/py_backend/functions.py
@@ -747,9 +747,9 @@ def _integrate(self, time_steps, capture_elements, return_timestamps):
         return outputs
 
 
-def ramp(slope, start, finish):
+def ramp(slope, start, finish=0):
     """
-    Implements vensim's RAMP function
+    Implements vensim's and xmile's RAMP function
 
     Parameters
     ----------
@@ -758,7 +758,7 @@ def ramp(slope, start, finish):
     start: float
         Time at which the ramp begins
     finish: float
-        Time at which the ramo ends
+        Optional. Time at which the ramp ends
 
     Returns
     -------
@@ -773,10 +773,13 @@ def ramp(slope, start, finish):
     t = time()
     if t < start:
         return 0
-    elif t > finish:
-        return slope * (finish - start)
     else:
-        return slope * (t - start)
+        if finish <= 0:
+            return slope * (t - start)
+        elif t > finish:
+            return slope * (finish - start)
+        else:
+            return slope * (t - start)
 
 
 def step(value, tstep):
@@ -808,7 +811,6 @@ def pulse(start, duration):
     t = time()
     return 1 if start <= t < start + duration else 0
 
-
 def pulse_train(start, duration, repeat_time, end):
     """ Implements vensim's PULSE TRAIN function
 
@@ -822,6 +824,31 @@ def pulse_train(start, duration, repeat_time, end):
     else:
         return 0
 
+def pulse_magnitude(magnitude, start, repeat_time=0):
+    """ Implements xmile's PULSE function
+    
+    PULSE:             Generate a one-DT wide pulse at the given time
+       Parameters:     2 or 3:  (magnitude, first time[, interval])
+                       Without interval or when interval = 0, the PULSE is generated only once
+       Example:        PULSE(20, 12, 5) generates a pulse value of 20/DT at time 12, 17, 22, etc.
+    
+    In rage [-inf, start) returns 0
+    In range [start + n * repeat_time, start + n * repeat_time + dt) return magnitude/dt
+    In rage [start + n * repeat_time + dt, start + (n + 1) * repeat_time) return 0
+    """
+    t = time()
+    small = 1e-6  # What is considered zero according to Vensim Help
+    if repeat_time <= small:
+        if abs(t - start) < time_step:
+            return magnitude * time_step
+        else:
+            return 0
+    else:
+        if abs((t - start) % repeat_time) < time_step:
+            return magnitude * time_step
+        else:
+            return 0
+    
 
 def lookup(x, xs, ys):
     """ Provides the working mechanism for lookup functions the builder builds """
diff --git a/pysd/py_backend/xmile/SMILE2Py.py b/pysd/py_backend/xmile/SMILE2Py.py
index 0d179d04..dde7cc18 100644
--- a/pysd/py_backend/xmile/SMILE2Py.py
+++ b/pysd/py_backend/xmile/SMILE2Py.py
@@ -23,26 +23,106 @@
 
 # Here we define which python function each XMILE keyword corresponds to
 functions = {
-    "abs": "abs", "int": "int", "exp": "np.exp", "inf": "np.inf", "log10": "np.log10",
-    "pi": "np.pi", "sin": "np.sin", "cos": "np.cos", "sqrt": "np.sqrt", "tan": "np.tan",
-    "lognormal": "np.random.lognormal", "normal": "np.random.normal",
-    "poisson": "np.random.poisson", "ln": "np.log", "exprnd": "np.random.exponential",
-    "random": "np.random.rand", "min": "min", "max": "max", "arccos": "np.arccos",
-    "arcsin": "np.arcsin", "arctan": "np.arctan",
+    # ===
+    # 3.5.1 Mathematical Functions
+    # http://docs.oasis-open.org/xmile/xmile/v1.0/csprd01/xmile-v1.0-csprd01.html#_Toc398039980
+    # ===
+    
+    "abs": "abs", 
+    "arccos": "np.arccos",
+    "arcsin": "np.arcsin", 
+    "arctan": "np.arctan",
+    "cos": "np.cos", 
+    "sin": "np.sin", 
+    "tan": "np.tan",
+    "exp": "np.exp", 
+    "inf": "np.inf", 
+    "int": "int",
+    "ln": "np.log", 
+    "log10": "np.log10",
+    "max": "max", 
+    "min": "min",
+    "pi": "np.pi",
+    "sqrt": "np.sqrt", 
+    
+    # ===
+    # 3.5.2 Statistical Functions
+    # http://docs.oasis-open.org/xmile/xmile/v1.0/csprd01/xmile-v1.0-csprd01.html#_Toc398039981
+    # ===
+    
+    "exprnd": "np.random.exponential",
+    "lognormal": "np.random.lognormal", 
+    "normal": "np.random.normal",
+    "poisson": "np.random.poisson", 
+    "random": "np.random.rand", 
+    
+    # ====
+    # 3.5.3 Delay Functions
+    # http://docs.oasis-open.org/xmile/xmile/v1.0/csprd01/xmile-v1.0-csprd01.html#_Toc398039982
+    # ====
+    
+    # "delay" !TODO!
+    # "delay1" !TODO!
+    # "delay2" !TODO!
+    # "delay3" !TODO!
+    # "delayn" !TODO!
+    # "forcst" !TODO!
+    # "smth1" !TODO!
+    # "smth3" !TODO!
+    # "smthn" !TODO!
+    # "trend" !TODO!
+    
+    # ===
+    # 3.5.4 Test Input Functions
+    # http://docs.oasis-open.org/xmile/xmile/v1.0/csprd01/xmile-v1.0-csprd01.html#_Toc398039983
+    # ===
+
+    "pulse": "functions.pulse_magnitude",
+    "step": "functions.step",
+    "ramp": "functions.ramp",
+    
+    # ===
+    # 3.5.5 Time Functions
+    # http://docs.oasis-open.org/xmile/xmile/v1.0/csprd01/xmile-v1.0-csprd01.html#_Toc398039984
+    # ===
+    # Should we include as function list or it provided by another way?
+    
+    # "dt" !TODO!
+    # "starttime" !TODO!
+    # "stoptime" !TODO!
+    # "time" !TODO!
+    
+    # ===
+    # 3.5.6 Miscellaneous Functions
+    # http://docs.oasis-open.org/xmile/xmile/v1.0/csprd01/xmile-v1.0-csprd01.html#_Toc398039985
+    # ===
     "if_then_else": "functions.if_then_else",
-    "step": "functions.step", "pulse": "functions.pulse"
+    # "init" !TODO!
+    # "previous" !TODO!
+    # "self" !TODO!
 }
 
 prefix_operators = {
     "not": " not ",
-    "-": "-", "+": " ",
+    "-": "-", 
+    "+": " ",
 }
 
 infix_operators = {
-    "and": " and ", "or": " or ",
-    "=": "==", "<=": "<=", "<": "<", ">=": ">=", ">": ">", "<>": "!=",
-    "^": "**", "+": "+", "-": "-",
-    "*": "*", "/": "/", "mod": "%",
+    "and": " and ", 
+    "or": " or ",
+    "=": "==", 
+    "<=": "<=", 
+    "<": "<", 
+    ">=": ">=", 
+    ">": ">", 
+    "<>": "!=",
+    "^": "**", 
+    "+": "+", 
+    "-": "-",
+    "*": "*", 
+    "/": "/", 
+    "mod": "%",
 }
 
 builders = {}
@@ -79,10 +159,16 @@ def parse(self, text, context='eqn'):
                 If context is set to equation, lone identifiers will be parsed as calls to elements
                 If context is set to definition, lone identifiers will be cleaned and returned.
         """
+        # !TODO! Should remove the inline comments from `text` before parsing the grammar
+        # http://docs.oasis-open.org/xmile/xmile/v1.0/csprd01/xmile-v1.0-csprd01.html#_Toc398039973
         self.ast = self.grammar.parse(text)
         self.context = context
         return self.visit(self.ast)
 
+    def visit_conditional_statement(self, n, vc):
+        _IF, _1, condition_expr, _2, _THEN, _3, then_expr, _4, _ELSE, _5, else_expr = vc
+        return "functions.if_then_else(" + condition_expr + ", " + then_expr + ", " + else_expr + ")"
+        
     def visit_identifier(self, n, vc):
         return self.extended_model_namespace[n.text] + '()'
 
diff --git a/pysd/py_backend/xmile/smile.grammar b/pysd/py_backend/xmile/smile.grammar
index 027c7a4e..119e00cf 100644
--- a/pysd/py_backend/xmile/smile.grammar
+++ b/pysd/py_backend/xmile/smile.grammar
@@ -1,4 +1,6 @@
-expr = _ pre_oper? _ primary _ (in_oper _ expr)?
+expr = conditional_statement / (_ pre_oper? _ primary _ (in_oper _ expr)?)
+
+conditional_statement = "IF" _ expr _ "THEN" _ expr _ "ELSE" _ expr
 
 primary  = call / parens / number / identifier
 parens   = "(" _ expr _ ")"
diff --git a/pysd/pysd.py b/pysd/pysd.py
index 22d4852b..4882a855 100644
--- a/pysd/pysd.py
+++ b/pysd/pysd.py
@@ -15,6 +15,7 @@
 
 def read_xmile(xmile_file):
     """ Construct a model object from `.xmile` file. """
+    from . import py_backend
     from .py_backend.xmile.xmile2py import translate_xmile
     py_model_file = translate_xmile(xmile_file)
     model = load(py_model_file)