Add the exponential function

teg/math/smooth.py

@@ -16,6 +16,7 @@ class Sqrt(SmoothFunc):
 
     NOTE: Does not check inputs are valid (x must be positive)
     """
+
     def __init__(self, expr: ITeg, name: str = "Sqrt"):
         super(Sqrt, self).__init__(expr=expr, name=name)
 
@@ -33,7 +34,8 @@ def output_size(input_size):
 
 
 class Sqr(SmoothFunc):
-    """y = x**2 """
+    """y = x**2"""
+
     def __init__(self, expr: ITeg, name: str = "Sqr"):
         super(Sqr, self).__init__(expr=expr, name=name)
 
@@ -51,7 +53,8 @@ def output_size(input_size):
 
 
 class Sin(SmoothFunc):
-    """y = sin(x) """
+    """y = sin(x)"""
+
     def __init__(self, expr: ITeg, name: str = "Sin"):
         super(Sin, self).__init__(expr=expr, name=name)
 
@@ -70,6 +73,7 @@ def output_size(input_size):
 
 class Cos(SmoothFunc):
     """y = cos(x)"""
+
     def __init__(self, expr: ITeg, name: str = "Cos"):
         super(Cos, self).__init__(expr=expr, name=name)
 
@@ -87,7 +91,8 @@ def output_size(input_size):
 
 
 class ASin(SmoothFunc):
-    """theta = asin(x) """
+    """theta = asin(x)"""
+
     def __init__(self, expr: ITeg, name: str = "ASin"):
         super(ASin, self).__init__(expr=expr, name=name)
 
@@ -105,7 +110,8 @@ def output_size(input_size):
 
 
 class ATan2(SmoothFunc):
-    """theta = atan2(x, y) """
+    """theta = atan2(x, y)"""
+
     def __init__(self, expr: ITeg, name: str = "ATan2"):
         super(ATan2, self).__init__(expr=expr, name=name)
 
@@ -121,3 +127,20 @@ def operation(self, in_value):
     def output_size(input_size):
         assert input_size == 2
         return 1
+
+
+class Exp(SmoothFunc):
+    def __init__(self, expr: ITeg, name: str = "Exp"):
+        super(Exp, self).__init__(expr=expr, name=name)
+
+    def fwd_deriv(self, in_deriv_expr: ITeg):
+        return Exp(self.expr) * in_deriv_expr
+
+    def rev_deriv(self, out_deriv_expr: ITeg):
+        return out_deriv_expr * Exp(self.expr)
+
+    def operation(self, in_value):
+        return np.exp(in_value)
+
+    def output_size(input_size):
+        return input_size