Градиентный спуск сделать параболу на графике

import numpy as np
import random
import matplotlib.pyplot as plt
import matplotlib.pyplot as plt2
import matplotlib.pyplot as plt3
import scipy as sp 
from pylab import rcParams
x1=[6,18,13,12,1,7,21,21,20,5,14,12]
x2=[55,66,47,39,39,42,42,45,62,65,48,39]
x3=[9,27,8,16,10,10,19,28,32,31,18,16]
x4=[26,22,15,15,12,15,9,8,27,15,16,15]
y=[103,94,151,154,154,143,102,177,76,105,150,154]
 
 
w0=np.arange(12)
w1=np.arange(12)
w2=np.arange(12)
w3=np.arange(12)
w4=np.arange(12)
w0[0]=4
w1[0]=5
w2[0]=1
w3[0]=3
w4[0]=9
 
sw0=np.arange(12)
sw1=np.arange(12)
sw2=np.arange(12)
sw3=np.arange(12)
sw4=np.arange(12)
sw0[0]=4
sw1[0]=5
sw2[0]=1
sw3[0]=3
sw4[0]=9
i=-1
 
'''градиентный спуск'''
for i in range(11):
  if (abs(w0[i]-w0[i-1])):
   w0[i+1]=(2/len(y)*np.sum((w1[i] * x1[i]+w2[i] * x2[i]+w3[i] * x3[i]+w4[i] * x4[i] + w0[i-1] - y[i])))
  if (abs(w1[i]-w1[i-1])):
   w1[i+1]=(2/len(y)*np.sum(x1[i]* (w1[i] * x1[i]+w2[i] * x2[i]+w3[i] * x3[i]+w4[i] * x4[i] + w0[i] - y[i])))
  if (abs(w2[i]-w2[i-1])): 
   w2[i+1]=(2/len(y)*np.sum(x2[i]* (w1[i] * x1[i]+w2[i] * x2[i]+w3[i] * x3[i]+w4[i] * x4[i] + w0[i] - y[i])))
  if (abs(w3[i]-w3[i-1])):
    w3[i+1]=(2/len(y)*np.sum(x3[i]* (w1[i] * x1[i]+w2[i] * x2[i]+w3[i] * x3[i]+w4[i] * x4[i] + w0[i] - y[i])))
  if (abs(w4[i]-w4[i-1])): 
    w4[i+1]=(2/len(y)*np.sum(x4[i]* (w1[i] * x1[i]+w2[i] * x2[i]+w3[i] * x3[i]+w4[i] * x4[i] + w0[i] - y[i])))
RSS=[]   
for i in range(len(y)):
    RSS.append(2/len(y)*np.sum(w0[i]-y+w1[i]-y+w2[i]-y+w3[i]-y+w0[i]-y)**2)
'''стохатический градиентный спуск'''   
for i in range(11):
    if (abs(sw0[i]-sw0[i-1])):
     sw0[i+1]=(2/len(y)*(sw1[i] * x1[i] + sw2[i] * x1[i] + sw3[i] * x1[i] +sw4[i] * x1[i] + sw0[i] - y[i]))
    if (abs(sw1[i]-sw1[i-1])):
     sw1[i+1]=(2/len(y)*(x1[i]* (sw1[i] * x1[i]+sw2[i] * x1[i]+sw3[i] * x1[i]+sw4[i] * x1[i] + sw0[i-1] - y[i])))
    if (abs(sw2[i]-sw2[i-1])): 
     sw2[i+1]=(2/len(y)*(x2[i]* (sw1[i] * x1[i]+sw2[i] * x1[i]+sw3[i] * x1[i]+sw4[i] * x1[i] + sw0[i-1] - y[i])))
    if (abs(sw3[i]-sw3[i-1])):
     sw3[i+1]=(2/len(y)*(x3[i]* (sw1[i] * x1[i]+sw2[i] * x1[i]+sw3[i] * x1[i]+sw4[i] * x1[i] + sw0[i-1] - y[i])))
    if (abs(sw4[i]-sw4[i-1])): 
     sw4[i+1]=(2/len(y)*(x4[i]* (sw1[i] * x1[i]+sw2[i] * x1[i]+sw3[i] * x1[i]+sw4[i] * x1[i] + sw0[i-1] - y[i])))
 
RSS2=[]   
for i in range(len(y)):
    RSS2.append(2/len(y)*np.sum(sw0[i]-y+sw1[i]-y+sw2[i]-y+sw3[i]-y+sw4[i]-y)**2)
print ("w0", w0)
print ("w1", w1)
print ("w2", w2)
print ("w3", w3)
print ("w4", w4)
print ("RSS: ", RSS)
 
print ("sw0", sw0)
print ("sw1", sw1)
print ("sw2", sw2)
print ("sw3", sw3)
print ("sw4", sw4)
print ("SRSS: ", RSS2)
 
RSS.sort(reverse=1)
RSS2.sort(reverse=1)
y.sort(reverse=1)
plt.plot(RSS)
plt.show()
plt.plot(RSS2)  
plt.show()