polyfit reference for linearity fit

EMVA1288 · Sep 23, 2016 · 46785cb · 46785cb
1 parent 553209a
commit 46785cb
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/emva1288/process/results.py b/emva1288/process/results.py
@@ -560,8 +560,10 @@ def linearity(self):
         ##################################################################
         # Following the emva1288 standart for the computation of the fit #
         ##################################################################
+
         X_ = X[imin: imax]
         Y_ = Y[imin: imax]
+
         xy = np.sum(X_ / Y_)
         xy2 = np.sum(X_ / (Y_ ** 2))
         x2y2 = np.sum((X_ / Y_) ** 2)
@@ -571,6 +573,9 @@ def linearity(self):
         b = ((xy * xy2) - (x2y2 * _y)) / ((xy2 ** 2) - (x2y2 * _y2))
         a = (xy - (b * xy2)) / x2y2
 
+        # The equivalent numpy polyfit is
+        # a, b = np.polynomial.polynomial.polyfit(X_, Y_, 1, w=1 / Y_)
+
         dev = 100. * (Y - (a * X + b)) / (a * X + b)
 
         lin = {}