diff --git a/FiCurve.py b/FiCurve.py
index 3903518..5d95a58 100644
--- a/FiCurve.py
+++ b/FiCurve.py
@@ -24,7 +24,7 @@ class FICurve:
 
         # f_max, f_min, k, x_zero
         self.boltzmann_fit_vars = []
-        # offset increase
+        # increase, offset
         self.f_infinity_fit = []
 
         self.all_calculate_frequency_points()
diff --git a/functions.py b/functions.py
index ab00e7c..3459db0 100644
--- a/functions.py
+++ b/functions.py
@@ -1,5 +1,6 @@
 
 import numpy as np
+from numba import jit
 
 
 def line(x, m, c):
@@ -37,8 +38,8 @@ def inverse_full_boltzmann(x, f_max, f_min, k, x_zero):
     return -(np.log((f_max-f_min) / (x - f_min) - 1) / k) + x_zero
 
 
-def clipped_line(x, a, b):
-    return np.clip(a+b*x, 0, None)
+def clipped_line(x, m, c):
+    return np.clip(m*x + c, 0, None)
 
 
 def inverse_clipped_line(x, a, b):
@@ -46,3 +47,10 @@ def inverse_clipped_line(x, a, b):
         raise ValueError("Value undefined in inverse_clipped_line.")
 
     return (x-a)/b
+
+
+@jit(nopython=True)  # useful in less that 1000x10000 calls (1000 tests with 10k data points)
+def rectify(x):
+    if x < 0:
+        return 0
+    return x