MAT491 - Lab 1

Q0.

  • Assign your name to a variable called "my_name".
  • Assign your student id to variable "stud_id".
  • Use variable "my_name" and "stud_id" to print your name and your student id using "print" function in the following format:

    Your Name - Your Student ID

  • For example:

    Ali bin Abu - 2000123456


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%pylab inline
import matplotlib.pyplot as plt
import numpy as np
from mpl_toolkits.mplot3d import Axes3D


Populating the interactive namespace from numpy and matplotlib

Parametric Equations

Example: Graph the curve $x = \sin{t}$, $y = \cos{t}$, $0 \le t \le \pi$.

Read Scipy Lecture Notes (http://www.scipy-lectures.org/) pg. 45 for creating arrays and pg. 83 for plotting.


In [2]:
# define array from 0 to pi with interval size 0.1
t = np.arange(0, np.pi, 0.1)

#define x and y
x = np.sin(t)
y = np.cos(t)

# plot the graph
plt.plot(x, y)
plt.show()


Q1. Graph the curve $x= 26 \sin^3{t}$, $y = 13\cos{t} - 5\cos{2t} - 2\cos{4t}$, $0 \le t \le 2\pi.$


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Q2. Graph the curve $x=\mathrm{e}^t \cos{t} - \mathrm{e}^t \sin{t}$, $y = \mathrm{e}^t \sin{t}$, $0 \le t \le \pi.$ Hint: Use np.exp(t) for $\mathrm{e}^t$.


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Polar Coordinates

Example: Sketch the curve $r = 1 + \sin{\theta}$.


In [3]:
# define array from 0 to pi 100 elements
theta = np.linspace(0, 2*np.pi, 100)  

# define $r = 1 + \sin{\theta}$
r = 1 + np.sin(theta)

# add subplot in polar coordinates 
ax = plt.subplot(111, polar=True)

# plot the graph
ax.plot(theta, r)
plt.show()


Q3. Sketch the curve $r = 1 + \cos{\theta}$.


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Q4. Sketch the curve $r = 1 - \cos{\theta}$.


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Quadratic Surfaces

Example: Sketch the graph of the surface $z = x^2$.


In [4]:
x = np.arange(-2, 2, 0.25)              # points in the x axis
y = np.arange(-2, 2, 0.25)              # points in the y axis
X, Y = np.meshgrid(x, y)                # create the "base grid"
Z = X**2                                # points in the z axis
fig = plt.figure()
ax = fig.gca(projection='3d')           # 3d axes instance
surf = ax.plot_surface(X, Y, Z,
                       rstride=2,           # row step size
                       cstride=2,           # column step size
                       linewidth=1,         # wireframe line width
                       cmap=cm.RdPu,        # colour map
                       antialiased=True)


Q5. Sketch the graph of the surface $z = x^2 - y^2$.


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Q6. Sketch the graph of the surface $z = x^2 + y^2$.


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Q7. Sketch the graph of the surface $z = y^2 - x^2$.


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End of question.