diff --git a/s2eps.py b/s2eps.py
index 51434f0..5093c8b 100644
--- a/s2eps.py
+++ b/s2eps.py
@@ -1,8 +1,10 @@
 #!/usr/bin/python3
 
 import numpy as np
+from numpy import pi
 from operator import itemgetter
 import matplotlib.pyplot as plt
+from scipy.optimize import fsolve
 
 def s2p_to_narray(file):
     """ prebere s2p file v narray. STOLPCI --> VRSTICE!!! """
@@ -20,28 +22,95 @@ def narray_to_s(narray):
     s['f'] = narray[0,:]
     return s
 
-def s_to_eps(s, L):
+def s_to_eps(s, L,fc):
     """ izracunam eps in tand iz s parametrov in dolzin """
     s11, s21, s12, s22, f = itemgetter(*s.keys())(s) 
+    c = 299792458 #hitrost svetlobe v vakuumu. 
 
-    X = (s11**2 - s21**2 + 1)/2/s11
-    G = X + np.sqrt(X**2 - 1)
-    Gm = X - np.sqrt(X**2 - 1)
+    K = (s11**2 - s21**2 + 1)/2/s11
+    G = K + np.sqrt(K**2 - 1)
+    Gm = K - np.sqrt(K**2 - 1)
     G[np.abs(G) > 1] = Gm[np.abs(G) > 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
+    T = (s11 + s21 - G)/(1-(s11+s21)*G)
+    Lambda2 = (1j/2/pi/L * np.log(T))**2
+    l0g2 = ( (f/c)**2 - (fc/c)**2 )**-1
+    print(l0g2*Lambda2)
+    test_plot(f, np.abs(l0g2*Lambda2))
+
+    return 0
+
+#Nicolson-Ross-Weir metoda -> NUMERICNO NESTABILNA
+#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)
+#    Gm = X - np.sqrt(X**2 - 1)
+#    G[np.abs(G) > 1] = Gm[np.abs(G) > 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 measured_group_delay(f,P)
+#
+#
+#naumi kako napisat sistem nelinearnih enacb in na kaj jih resevat!
+#def iterative(s,fc,L,Lair):
+#    s11, s21, s12, s22, f = itemgetter(*s.keys())(s) 
+#    c = 299792458 #hitrost svetlobe v vakuumu. 
+#
+#    p0 = 1j*np.sqrt( (2*np.pi*f/c)**2-(2*np.pi*fc/c)**2)
+#    z = lambda p,L: np.exp(-p*L)
+#    G = lambda p: (p0-p)/(p0+p) #predpostavim permeabilnost = 1
+#
+#    f1 = lambda p,L,Lair: np.abs(s21) - np.abs(z(p,L)*(1-G(p)**2)/(1-z(p,L)**2*G(p)**2))
+#    f2 = lambda p,L,Lair: np.abs(s11) - np.abs(G(p)*(1-z(p,L)**2)/(1-z(p,L)**2*G(p)**2))
+#    f3 = lambda p,L,Lair: (s21*s12-s11*s22)-np.exp(-p0*(Lair-L))*(z(p,L)**2-G(p)**2)/(1-z(p,L)**2*G(p)**2)
+#
+#    p,l,l_air = fsolve([f1,f2,f3],[p0,L,Lair])
+#
+#    return p,l,l_air
+#
+
+def sistem_enacb(s, fc, beta, L):
+    """ sistem enacb za iterativno iskanje dielektricnosti
+    predpostavim mu=1 
+    
+    X = [g, eps, T, G]"""
+    s11, s21, s12, s22, f = itemgetter(*s.keys())(s) 
+    c = 299792458 #hitrost svetlobe v vakuumu. 
+
+    g0 = 2j*pi*f/c*np.sqrt(1-(fc/f)**2)
+
+    # desne strani enacb
+    T = lambda g: np.exp(-g*L) 
+    g = lambda eps: 2j*pi*f/c*np.sqrt(eps-(fc/f)**2) # g
+    G = lambda g: (g0-g)/(g0+g)
+
+    # pomozne funkcije za zadnjo enacbo
+    h1 = lambda T,G: T*(1-G**2)/(1-T**2*G**2)
+    h2 = lambda T,G: G*(1-T**2)/(1-T**2*G**2)
+
+
+    f1 = lambda X: X[2]-T(X[0]) # T
+    f2 = lambda X: X[0]-g(X[1]) # g
+    f3 = lambda X: X[3]-G(X[0]) #G
+    f4 = lambda X: s21+beta*s11-h1(X[2],X[3])-beta*h2(X[2],X[3])
+
+    return lambda x: [f1(x),f2(x),f3(x),f4(x)]
+
+def iterative(s, L, fc):
+    c = 299792458 #hitrost svetlobe v vakuumu. 
+    f = s['f']
+    g0 = 2j*pi*f/c*np.sqrt(1-(fc/f)**2)
+    f = sistem_enacb(s, fc, 0.5, L)
+    return f
 
-    return measured_group_delay(f,P)
 
 def measured_group_delay(f, P):
     phase = np.unwrap(np.angle(P))
     test_plot(f,phase)
-    # zgladim fazo s polinomsko aproksimacijo druge stopnje
-    #ph = np.polyfit(f,phase,2)
-    #print(ph)
-    #faza = ph[2]+ph[1]*f+ph[0]*f**2
-    #test_plot(f,faza-phase)
     return -np.diff(phase)/np.diff(f)/2/np.pi
 
 def test_plot(x,*args):
@@ -49,8 +118,9 @@ def test_plot(x,*args):
         plt.plot(x,y)
     plt.show()
 
-a=s2p_to_narray('20.s2p')
+### testni klici
+a=s2p_to_narray('teflon.s2p')
 b = narray_to_s(a)
 locals().update(b)
-c= s_to_eps(b,6e-2)
-test_plot(f[:-1],c)
+print(iterative(b,6e-2,6.557e9))
+#c = s_to_eps(b, 6e-2,6.557e9)