Не рисует график функции

import math
%matplotlib inline
import matplotlib.pyplot as plt
from scipy import stats
import numpy as np
 
import warnings
import matplotlib.cbook
warnings.filterwarnings("ignore",category=matplotlib.cbook.mplDeprecation)
 
Y = [1.0, 1.34, 1.75, 2.18, 2.53, 2.71, 2.65, 2.37, 1.97, 1.54, 1.16, 0.86, 0.64, 0.5, 0.42, 0.37, 0.36, 0.39, 0.45, 0.56, 0.74]
n = int(input('n ='))
m = int(input('m ='))
i = (2 * n) + 1
j = m + 1
x = 0
minX = 0
maxX = 0
 
for t in range(i):
    X = (2 * math.pi * t)/(2 * n + 1)
    if X <= minX:
        minX = X
    if X >= maxX:
        maxX = X
    print('X =', X)
print('minX =', minX)
print('maxX =', maxX)
 
SumY = 0
for t in range(len(Y)):
    SumY = SumY + Y[t]
print('SumY =', SumY)
 
a0 = 1 / (2 * n + 1) * SumY
print('a0 =', a0)
 
a = np.array([1, 1, 1, 1 ,1, 1])#ak
for f in range(6):
    SumYcos = 0
    for t in range(len(Y)):
        SumYcos = SumYcos + (Y[t] * math.cos(math.radians((2 * math.pi * f * t) / (2 * n + 1))))
        a[f] = SumYcos
 
z = 0
for t in range(len(a)):
    print('ak', z, '=', a[z])
    z += 1
 
ab = [1, 1, 1, 1 ,1, 1]#bk
for f in range(6):
    SumYsin = 0
    for t in range(len(Y)):
        SumYsin = SumYsin + (Y[t] * math.sin(math.radians((2 * math.pi * f * t) / (2 * n + 1))))
        ab[f] = SumYsin
 
z = 0
for t in range(len(a)):
    print('bk', z, '=', a[z])
    z += 1
 
Sum = 0
for t in range(6):
    Sum = Sum + (a[t] * math.cos(math.radians(t * x)) + ab[t] * math.sin(math.radians(t * x)))
print('Sum =', Sum)
 
Px = a0 + 2 * Sum
print('Px =', Px)
 
fig = plt.figure()
ax = plt.axes()
iks = np.linspace(-10, 10, 10)
 
for t in range(j):
    x = minX + t * ((maxX - minX)/m)
    #print('x =', x)
    Sum = 0
    for l in range(6):
        Sx = a0 + 2 * np.sum(a[l] * np.cos(l * x) + ab[l] * np.sin(l * x))
        ax.plot(x, Sx, color = 'red');