EENG 1910: Project I – Introduction to Electrical Engineering
Assignment-9
To copy the resulting figures in the problems below to Word,
Click Edit on the figure window, then Copy Figure and paste into
your Word document.
Problem-1: Plotting in Different Figure Windows
Plot sin(x) for x values ranging from 0 to 2 (use the linspace
function or column operator) in two separate figure windows (Use
figure(1), figure(2))
- using 10 points in this range - using 100 points in this range
Annotate your figures and provide an explanation of the
difference observed in the two figures.
Problem-2: Subplot
Use subplot to show the difference between the sin and cos
functions. Create an x vector with 100 linearly spaced points in
the range from –2 to 2, and then two y vectors (y1 and y2) for
sin(x) and cos(x). In a 2x1 subplot, use the plot function to
display them, with appropriate titles.
Problem-3: Plotting, Labelling, Hold On/Off
Plot 𝑦 = exp(𝑥) in the interval [-3, 3] using a solid line. Now
plot a linear approximation of 𝑒 𝑥 (i.e. 𝑦 = 𝑥) using a dashed line with a square marker in a different color and a quadratic
approximation of 𝑒 𝑥 (i.e. 𝑦 = 1 + 𝑥 + 𝑥 2
2 ) using a dotted line and a
circle marker in another color. Title the plot “Plots of
Approximations of exp(𝑥).” Label the y-axis as “Approximations
of exp(𝑥)” and the x-axis as “𝑥”. Use legend to appropriately identify the plotted lines. Set axes limits to [-3, 3, -5, 15].
Note: Make sure to define 𝑥 with sufficient data points to avoid obtaining choppy curves. Use hold on/hold off to obtain the
three curves on the same figure.
Problem-4: Bar Chart, Histogram, Subplot
Let the vector
Grades = [68, 83, 61, 100, 80, 95, 45, 100, 70, 75, 82, 57, 5,
76, 85, 62, 71, 96, 78, 76, 68, 72, 75, 83, 87, 89, 99, 93, 100,
100, 80, 96, 100, 98, 45, 96, 89, 86, 99, 90, 70]
represent the distribution of final grades in an engineering
course.
a. Use MATLAB to sort (sort) the grades. Then, using the subplot
function subdivide the figure window into two rows and one
column that shows the following:
(1) A bar (bar) graph of the sorted scores,
(2) A histogram (hist) of the sorted scores.
b. Using length or numel along with the find function, provide
the command that will return the number of students that
received A, B, C, D, and F in this class assuming that A
corresponds to grades greater or equal to 90, B corresponds to
grades greater or equal to 80 but less than 90, etc.
The results should be displayed in statements as the ones below:
9 students received A in this class.
8 students received B in this class.
.
Note: Annotate the resulting figure appropriately.
Problem-5: Subplot
Create a MATLAB script to plot the functions defined below
provided x = 0:pi/20:2*pi. All the plots should be on the same
figure in the format of a 2-by-2 matrix. Each of the subfigures
should have a title, and labels.
f1(x) = cos(x)
f2(x) = sin(2*x)*sin(3*x)
f3(x) = 1/cos(2*x)
f4(x) = cos(x^2) + 2*sin(x^2)
Problem-6: Bar Chart
Let’s assume that the three lines of data below represent years,
median incomes, and median home prices for the city of Dallas.
The dollar amounts (median incomes and median home prices) are
in thousands.
2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
72 74 74 77 49 53 89 93 95 85 100 120
275 270 300 310 150 250 410 380 300 421 500 486
Create a horizontal stacked bar chart to display the above
information, with an appropriate title.
The ratio of the home price to the income is called the “housing
affordability index.” Calculate this for every year and plot it.
The x-axis should show the years (e.g., 2004 to 2015).
In what year(s) houses were affordable in Dallas? Why?
Problem-7: Pie Chart
The number of students in each engineering department at UNT is:
EE 255
CS 421
CE 376
ET 142
ME 98
Draw a pie chart to show the percentage of students in each
department. Make sure that you have appropriate titles, labels,
and legends on your chart.
What other chart could be used to represent this, and why?
Your output should be similar to the one in the figure below:
Problem-8: Testing
What is the importance of testing in engineering design? Provide
couple examples of real-life situations or projects where
thorough testing should have been performed and the consequences
that resulted in poor testing.