python isn't plotting the “tangent” function correctly

Question

I'm trying to plot the general tangent function onto matplotlib in Python but it is coming out incorrectly.

The function I'm trying to plot is: $$ f(x) = A tan( \\frac{2\\pi}{\\lambda} x - \\phi ) $$

import numpy as np
import math
import matplotlib.pyplot as plt
import tkinter

f = lambda x, A, lambda_, phi: A * math.sin( ((2 * math.pi) / lambda_) * x - phi)
g = lambda x, A, lambda_, phi: A * math.cos( ((2 * math.pi) / lambda_) * x - phi)
h = lambda x, A, lambda_, phi: f(x, A, lambda_, phi) / g(x, A, lambda_, phi)

def generate_graph(A, lambda_, Phi):
    plt.figure()
    x = np.arange(-.95, .95, 0.005)
    #plt.plot(x, [f(k, A, lambda_, Phi) for k in x], color='red')
    #plt.plot(x, [g(k, A, lambda_, Phi) for k in x], color='blue')
    plt.plt(x, [h(k, A, lambda_, Phi) for k in x], color='green')
    plt.show()

A = 1 #amplitude
lambda_ = 3 #wavelength
Phi = 0 #phase shift

generate_graph(A, lambda_, Phi)

It's supposed to look like this:

But it ends up looking like this:

Answer 1

This happens due to singularities of the tangent function (ie, having x values around those points). A quick fix would be to restrict the y-axis with, eg,

plt.ylim(-40, 40)

giving