diff --git a/.s2eps.py.swp b/.s2eps.py.swp
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Binary files /dev/null and b/.s2eps.py.swp differ
diff --git a/s2eps.py b/s2eps.py
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--- /dev/null
+++ b/s2eps.py
@@ -0,0 +1,38 @@
+#!/usr/bin/python3
+
+import numpy as np
+from operator import itemgetter
+
+def s2p_to_narray(file):
+    """ prebere s2p file v narray. STOLPCI --> VRSTICE!!! """
+    return np.loadtxt(file, comments=('!','#')).T
+
+def narray_to_s(narray):
+    """ prebran s2p narray posortiram po s parametrih.
+        pri tem upostevam vrstni red:
+        f s11 s21 s12 s22, kjer sta za vsak s parameter
+        dve vrstici: realni in imaginarni del """
+    keys = ["s{}{}".format(j,i) for i in range(1,3) for j in range(1,3)]
+    s = {}
+    for i in range(4):
+        s[keys[i]] = narray[(2*i+1),:]+1j*narray[(2*i+2),:]
+    s['f'] = narray[0,:]
+    return s
+
+def s_to_eps(s, L):
+    """ izracunam eps in tand iz s parametrov in dolzin """
+    s11, s21, s12, s22, f = itemgetter(*s.keys())(s) 
+
+    X = (s11**2 - s21**2 + 1)/2/s11
+    G = X + np.sqrt(X**2 - 1)
+    if np.abs(G) > 1:
+        G = X - np.sqrt(X**2 - 1)
+    P = (s11 + s21 - G)/(1-(s11+s21)*G)
+    Lambda2 = - (1/2/np.pi/L * np.log(1/P))**2 #izmisli resitev za korene kompleksnega logaritma
+    # argument korena mora biti 2*pi*n, kjer je n=L/lambda_g
+
+    return
+
+a=s2p_to_narray('20.s2p')
+b = narray_to_s(a)
+s_to_eps(b,0,0,0)