Matplotlib plot with 1/T and second units

Second yticks and xticks

import numpy as np
import matplotlib.pyplot as plt

fig = plt.figure()
ax1 = fig.add_subplot(111)
ax2 = ax1.twiny()

X = np.linspace(1,1000,1000)
Y = np.cos(X/200)

ax1.plot(X,Y)
ax1.set_xlabel(r"Original x-axis: $X$")

new_tick_locations = np.array([300, 200, 100])

def tick_function(X):
    V = 1/X
    return ["%.3f" % z for z in V]

ax2.set_xlim(ax1.get_xlim())
ax2.set_xticks(new_tick_locations)
ax2.set_xticklabels(tick_function(new_tick_locations))
ax2.set_xlabel(r"Modified x-axis: $1/(1+X)$")


new_tick_locations = np.array([1, 0.5, -0.75])

ax3 = ax1.twinx()
ax3.set_ylim(ax1.get_ylim())
ax3.set_yticks(new_tick_locations)
ax3.set_yticklabels(tick_function(new_tick_locations))
ax3.set_ylabel(r"Modified x-axis: $1/(1+X)$")

plt.show()