Using Python to graph relativistic apparent speed as a starship approaches c

#!/usr/bin/python3
import matplotlib.pyplot as plt
import numpy as np
fig, ax = plt.subplots(figsize=(8,6))
major_ticks = np.arange(0, 101, 5)
unit_ticks = np.arange(0, 101, 1)
minor_ticks = np.arange(0, 101, 0.2)
ax.set_xticks(major_ticks)
ax.set_yticks(major_ticks)
ax.set_xticks(unit_ticks, minor=True)
ax.set_yticks(unit_ticks, minor=True)
ax.grid(which='major', color='gray', linestyle='-', linewidth=0.8, alpha=0.8)
ax.grid(which='minor', color='black', linestyle='-', linewidth=0.5, alpha=0.7)
x = np.arange(0.7, 0.999, 0.0001)
y = x / np.sqrt(1 - x**2)
plt.plot(x * 100, y, color='blue', linewidth=2)
ax.set_xlim(70, 100)
ax.set_ylim(0, max(y)*1.1)
plt.xlabel("Real speed (percentage of c)")
plt.ylabel("Apparent speed (multiple of c)")
plt.tight_layout()
plt.show()