辅导MMM 1041、辅导MATLAB程序设计

日期：2023-11-01 07:17

MMM 1041 Computer programming with MATLAB
Coursework 1
Introduction:
This coursework is designed to help you revise your basic MATLAB knowledge that you
have gained in lectures 1-3. For each question you should write a script that contains the
answers. Save your scripts to disk with some sensible name for example, the Fle
containing the code for question one could be called Q1.m. Once you have Fnished all
the questions (or as many as you can manage), zip all your scripts up into a single zip Fle
and upload this to moodle. Name the zip Fle using the following format
Firstname_surname_studentid.zip. So for example my zip Fle would be called:
yong_ren_01234567.zip
In each .m Fle you generate, put on the Frst line your name and e-mail address – the
markers will use this e-mail address to give you feedback. For questions which require
you to write English sentences just include these as comments using the '%' character in
a script Fle. Try to include comments in the script Fles describing what the program is
doing – you will get marks for this.
Finally, please remember this is individual work and not group work. Work handed in
must be entirely your own and not copied from anyone else. By all means discuss the
coursework with your friends BUT then go away and write the programs yourself.
Q1: Variables
Evaluate the following functions at x=1.5
a) a=sin(x )
b) b=sin2
(x)
c) c=x
5
+x
4
+x
3
+x
2
+x
1
d) d=exp(sin(x )cos(x))
e) e=(x+1)(x?1)(x
2
+1)(x
3
)cos(x)
f) z=a+b
g) f =a+b
c+e
Q2: Arrays and plotting
a) Write a script to generate an array called 'x' with 100 points between -2p and 2p
Then evaluate the following functions between -2p and 2p
b) a=sin(x )
c) b=cos( x)
1
E
V
d) c=tan(x)
e) d=(e
x
?e
?x
)/2
f) Plot graphs of a and c
g) Calculate the mean, standard deviation of the data in array b.
h) Can you guess why the mean is not exactly zero?
Q3) Program How
A space capsule will re-enter the earths atmosphere from
space. The computer in the capsule uses it's radar to
check how high it is every 100ms, once the capsule is
only 1000 meters from the sea it deploys the parachute.
Once the capsule has hit he sea, the computer turns on a
transponder beacon which sends out radio signal
communicating the capsule's position to the rescue
ships.
Both deploying the parachute and turning on the
transponder beacon are handled by one program. Using
boxes to represent actions and diamonds to represent
decisions, sketch the structure of this program. The
program must contain the following boxes:
? Am I below 1000m?
? Am I at or below 0m?
You can use any program you want to do the sketch but export it to a pdf to make sure
the marker can open it. Include the pdf in your zip Fle as Q3.pdf.
Q4: Solving equations
a) Write a script to solve the following polynomial using the quadratic formula
x=?b±√b
2
?4 ac
2 a
270x2
+140x+1200 = 0
a=270
b=140
c=1200
2
Figure 1: An Apollo capsule
parachuting to an ocean landing
占
N
b) The speed of light in any material is given by the equation c=√ 1
?r ?0 μ0
where 'c' is the speed of light, the permittivity of free space is ε0=8 . 85418782 × 10-12
(m-3 kg-1 s4 A2
) and the magnetic permeability is μ0=4 π×10?7 (kg m s-2 A?2) . The value
of the relative permittivity ?r , changes as a function of temperature according to the
equation ?r=3( 1+
T?300
100 ) where T is given in Kelvin. Write a script to calculate the
speed of light at 400 kelvin, where ?r , ε0 , T, μ0 are deFned as separate variables.
Q5) Give an example of the use of the following commands and describe in no more than
10 words per command, what the following commands do (Hint, the last two you can Fnd
in the MATLAB help). Use the '%' to include English text in your .m Fle:
a) clear
b) who
c) a semicolon do after a line.
d) sound
e) roots
f) abs
Use the comment character '%' to include you description under you example in the .m
Fle.
Q6: Processing 1D arrays
Whales keep becoming beached in the Lyme Regis on the
south coast of the UK. Your small company is developing an
underwater acoustic system to keep whales of the beach.
The system will work by using an underwater speaker system
which plays a whale distress call. It is your job to prepare the
digital sound Fle which the system will use. By working in
collaboration with a marine biologist you have obtained a
recording of whale song. You can Fnd this Fle in whale.zip on
moodle, download the zip Fle and extract the Fle
whale.dat.
Write a script to:
a) Load the Fle into an array called 'song', and plot a graph of
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Figure 2: Whales in the
Atlantic.
the whale song. Using MATLAB, label the axis and put a title on the graph.
b) Make your script play the sound using the sound command. Hint: It plays 44100
samples (numbers) per second this must be the second argument to the sound
command). What happens if you play more/less than 44100 samples per second? Write
your answer in your script as a comment.
c) How many distinctive whale calls are there in the data, you should also be able to tell
this from looking at the graph. Write this as a comment in the script.
d) Use the size command to Fnd out how long the array song is, store the answer in a
variable.
e) The second whale call in the sample is the distress call you are interested in. By
looking at the numbers on the x-axis of your graph you will be able to tell at what position
in the array this distress call starts and ends. Make a second array which only contains
the distress call this should be called 'distress'.
f) Use the size command to Fnd out how long the array 'distress' is.
g) Your company wants the device you are designing to play 10 whale distress sounds in
a row one after each other. Make a new array containing ten distress calls one after each
other, and edit your script to play this sound.
h) How long is this array? If the computer turning 44100 elements per second, make your
script calculate the length of your new clip in seconds. To do this, Frst calculate the
length of the new array using the size command. Hint: The size function actually returns
a 2D array, containing the x and y size of any array. To do the calculation you will Frst
have to extract the correct element from the 2D array returned by the size function.
Q7: 2D Arrays
You are an engineer on a ship searching for oil. The ship has produced a topological (sea
depth) map of an area of interest. Your company now wants to drill a test well, however,
there are many underwater mountains around the site of interest. It is your job to
examine the topological data being produced by the ship and Fnd a suitable iat region
on the sea bed in which to drill.
a) The ship produces 2D topological (height) data and outputs this in a Fle called
'sea_bed.dat'. Load this Fle into an array and produce a 3D plot of the data. Hint:
MATLAB joins the points in 2D graphs with black lines by default, if there are lots of data
points this can make the graph look messy. Try adding the parameters
,'edgecolor','none' to the plot command to Fx this.
b) The height data in the Fle sea_bed.dat which the computers on the ship generated is
incorrect due to a miscalibration of the instruments in the ship. To correct for this error
you need to subtract 300 m from each data point in the array, the array will then give the
exact depth of each location below the sea's surface. Generate a new 2D array which
contains the corrected data and plot this.
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c) Label the x, y and z axis of your plot. The ship records data in a resolution of one
data point per meter.
d) Calculate the size of the array contained within sea_bed.dat. Store the the x and y size
in separate variables, and then calculate the total area of your map in a third variable.
e) Locate a region on the sea bed which is relatively iat. Extract this region from the 2D
array to form a new array called drilling_site. Produce a 3D plot of this region, again label
the axis.
f) Now extract a single 1D slice across, your chosen drilling location. Plot this as a 1D
graph.
g) Calculate the maximum, minimum and standard deviation of 1D data strip taken
across your proposed drilling site.
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