Бинарный поиск (дихотомия). Эксперимент расходится с теорией. Где ошибка?

#!/usr/bin/python3
 
import random
 
import glob, os
for f in glob.glob("*.txt"):
    os.remove(f)
 
import time
 
for ii in range(0, 10000, 100):
 
    array_start = 0
    array_end = ii
 
    for i in range(1, 101):
        start_time = time.time()
        x = array_start
        y = array_end
 
        number = random.randint(x, y)
 
        guess = (x + y) // 2
        tries = 1
 
        if guess == number:
            print(i, tries, time.time() - start_time, file=open("0-" + str(ii) + ".txt", "a"))
        else:
            while guess != number:
                if number > guess:
                    x = guess + 1
                    guess = (x + y) // 2
                    tries += 1
                elif number < guess:
                    y = guess - 1
                    guess = (x + y) // 2
                    tries += 1
            print(i, tries, time.time() - start_time, file=open("0-" + str(ii) + ".txt", "a"))

#!/usr/bin/python3
 
import matplotlib as mpl
import matplotlib.pyplot as plt
import math
import re
import numpy as np
 
import glob, os
for f in glob.glob("total_*.txt"):
    os.remove(f)
 
mpl.rcParams.update({'font.size': 10})
 
count_tries = []
count_steps = []
count_times = []
with open("0-900.txt") as f:
    for line in f:
        tries, steps, times = line.split()
        count_tries.append(int(tries))
        count_steps.append(int(steps))
        count_times.append(float(times))
 
print(np.mean(count_steps), np.mean(count_times))
 
print("!!!")
 
dpi = 80
 
fig1 = plt.figure(dpi = dpi, figsize = (1024 / dpi, 512 / dpi) )
plt.bar(count_tries, count_steps)
plt.title("Steps by tries (Число шагов поиска числа от числа запусков)")
plt.xlabel("Tries, counts (Запуски, шт)")
plt.ylabel("Steps, counts (Шаги поиска, шт)")
plt.grid(linestyle = "-")
fig1.savefig("0-900_steps.png")
 
print("!!!!")
 
fig2 = plt.figure(dpi = dpi, figsize = (1024 / dpi, 512 / dpi) )
plt.bar(count_tries, count_times)
plt.title("Times by tries (Время поиска числа от числа запусков)")
plt.xlabel("Tries, counts (Запуски, шт)")
plt.ylabel("Times, secs (Время, сек)")
plt.grid(linestyle = "-")
fig2.savefig("0-900_times.png")
 
print("!!!!!")
 
count_steps = []
count_tries = []
count_times = []
for i in range(0, 10000, 100):
    filename = "0-" + str(i) + ".txt"
    f = open(filename)
    for line in f:
        tries, steps, times = line.split()
        count_tries.append(int(tries))
        count_steps.append(int(steps))
        count_times.append(float(times))
 
    print(i, np.mean(count_steps), np.std(count_steps), file=open("total_steps.txt", "a"))
    print(i, np.mean(count_times), np.std(count_times), file=open("total_times.txt", "a"))
 
print("!!!!!!")
 
mean_array_steps = []
err_array_steps = []
array_length = []
with open("total_steps.txt") as f:
    for line in f:
        length, mean_steps, err_steps = line.split()
        array_length.append(int(length))
        mean_array_steps.append(float(mean_steps))
        err_array_steps.append(float(err_steps))
 
fig3 = plt.figure(dpi = dpi, figsize = (1024 / dpi, 512 / dpi) )
plt.errorbar(array_length, mean_array_steps, yerr = err_array_steps, color = "blue", label = "Experimental")
 
Fx = []
log_vals = []
x = 1.0
while x < 10000:
    log_vals += [ math.log(x, 2) ]
    Fx += [ x ]
    x += 0.1
plt.plot(Fx, log_vals, color = 'red', linestyle = 'solid', label = 'Theoretical')
 
plt.legend(loc = "lower right")
plt.title("Mean steps by array length (Среднее число шагов от длины отрезка)")
plt.xlabel("Length, number (Длина отрезка, число)")
plt.ylabel("Mean steps, counts (Среднее число шагов, число)")
plt.grid(linestyle = "-")
fig3.savefig("total_steps_length.png")
 
print("!!!!!!!")
 
mean_array_times = []
err_array_times = []
array_length = []
with open("total_times.txt") as f:
    for line in f:
        length, mean_times, err_times = line.split()
        array_length.append(int(length))
        mean_array_times.append(float(mean_times))
        err_array_times.append(float(err_times))
 
fig4 = plt.figure(dpi = dpi, figsize = (1024 / dpi, 512 / dpi) )
plt.errorbar(array_length, mean_array_times, yerr = err_array_times, color = "blue", label = "Experimental")
plt.title("Mean times by array length (Среднее время от длины отрезка)")
plt.xlabel("Length, number (Длина отрезка, число)")
plt.ylabel("Mean times, secs (Среднее время, сек)")
plt.grid(linestyle = "-")
fig4.savefig("total_times_length.png")