%% CSCI_1190 Quiz_3 for Fall 2016
% Your Name: Shuxian Zhao
%% Q1(3%) Write a command to create a 3 x 2 array with any values you choose.
% Place your answer here:
a=[1 2;3 4;5 6]
%% Q2(4%)
% Use A, B, and C below to create vector Y and
% output to the command window as follows:
%
% Y =[1 3 5 7 11 13 17 19 23]
%
A=[1 3 5];
B=[7 11 13];
C=[17 19 23];
% Place your answer here:
Y= [A B C]
%% Q3(5%)
M1=magic(5)
% The above magic command generates the following array M1
% M1 =
% 17 24 1 8 15
% 23 5 7 14 16
% 4 6 13 20 22
% 10 12 19 21 3
% 11 18 25 2 9
%
% Write a command to slice M1 to get the array M2 as follows:
%
% M2 =
% 6 22
% 18 9
M2=M1([3 5],[2 5])
%% Q4 (5%)
A = magic(10)
% Write a command to output all elements of the third column form A in the Command Window.
A(1:end, 3)
%% Q5 (5%)
clear, clc
Y =[ 2:2:7; 6:2:11; 11:2:15]
% Write a command to change the value 8 to 18 in the matrix Y
% using the subscripts of the array.
% Write your answer here:
Y(2,2)=18
%% Q6 (5%)
E = [3 4 5 6 7]
% Write a command to raise each element of E to power 3.
% Write your answer here:
E=E.^3
%% Q7 (3%)
% Write the MATLAB command that displays variables in the Workspace,
% along with each variable’s size, bytes, and class?
% Write your answer here:
whos
%% Q8 (8%)
% Write a MATLAB code to implement the following mathematical expression:
%
% E= ln(15) x e^2 x sin(60) x log(100)
%
% Note 1: 60 is an angle in degree
% Note 2: “ln(15)” refers to a natural logarithm.
% Note 3: log(100) refers to a base 10 logarithm.
% Write your answer here:
E=log(15)*exp(2)*sind(60)*log10(100)
%% Q9(5%)
% A vector M is given as follows:
M = [ 5, -1, 4, -10, 20, 0, -50, 35];
% Write a MATLAB command to display the smallest value of M and its index.
% Write your answer here:
[M,I] = min(M)%% Q10(10%)
% In this question, you first create a theta vector using the range operator.
% The theta’s first value is 0, the increment is 0.1, and the ending value is
% 2*pi. Then you plot two circles as shown in the separated file Quiz3.pdf.
% Place your answer here:
theta=[0:0.1:2*pi];
x=1*cos(theta);
y=1*sin(theta);
figure(1);
subplot(1,2,1);
plot(x,y);
subplot(1,2,2);
plot(x,y,’ro’);
%% Q11
% Write a function to convert temperatures between Celsius
%and Fahrenheit.
% The detailed requirements:
% The function name: tconv
% The function takes two parameters: degree and scale(F
% or C)
% The function returns a converted temperature
% The tconv function provides the help message as shown
% in the above
% three lines.
% If the input scale character is F, convert the degree
%to its C scale
% The formula converting a Fahrenheit to its Celsius
% counterpart:
% ¡ãc = (¡ãf – 32) x 5/9
%
% The formula converting a Celsius to its Fahrenheit
% counterpart:
% ¡ãf = ¡ãc x 9/5 + 32
%% Q12(12%) This question is related to the above question Q11.
% The following three steps are expected to write a script:
% Step 1: Write commands to input a temperature value and a scale letter,
% and prompt with the following text:
%
% ‘Please input a temperature degree: ‘
% ‘Please input a temperature scale F or C: ‘
%
% write your code here:
d=input(‘Please input a temperature degree:’);
s=input(‘Please input a temperature scale F or C:’,’s’);
% Step 2: Call tconv function you implemented in Q11 for conversion.
% Place your code here:
[Temperature,Scale]=tconv (d,s);% Step 3:
% Use fprintf to display the result in the Command Window.
%
% The output examples:
% 60.000000 F = 15.555556 C
% or
% 20.000000 C = 68.000000 F
%
% Note: You may need to use the if … else statment to dynamically decide
% the output scale letter as shown in the above output examples.
%
fprintf(‘%f %s = %f %sn’,d,s,Temperature,Scale);
%% Q13(15%)
% The “scores” array below has test scores.
% Use a for loop, and if … else statment for following requirements:
% Display ‘A’ if a score if greater than or equal to 90
% Display ‘B’ if a score if greater than or equal to 80
% Display ‘C’ if a score if greater than or equal to 70
% Display ‘D’ if a score if greater than or equal to 60
% Display ‘F’ otherwise
%
% Use the fprintf command to output the following:
% 1. The number of students who got B above. Example:
% “20 students among total 35 got B above.”
% 2. The percentage of the students who passed the exam
% if his/her score is greater than or equal to 60. Example:
% “Over 94.285714 percent students passed the exam.”
clear, clc
scores = [95, 83, 83, 95, 83, 76, 65, 85, 100, 65, 82, 95, …
66, 85, 95, 72, 82, 75, 60, 65, 66, 90, 55, …
100, 86, 75, 50, 90, 65, 80, 75, 66, 90, 86, 100];
m=0;
n=0;
P=0;
for i=1:35
if scores(i)>=90;
disp(‘A’);
m=m+1;
P=P+1;
elseif scores(i)>=80 && scores(i)<90;
disp(‘B’);
n=n+1;
P=P+1;
elseif scores(i)>=70 && scores(i)<80;
disp(‘C’);
P=P+1;
elseif scores(i)>=60 && scores(i)<70;
disp(‘D’);
P=P+1;
else
disp(‘F’);
end
end
fprintf(‘%d among total 35 got B above.n’,m+n);
percentage=(P/35)*100;
fprintf(‘Over %f percent students passed the exam.’,percentage);
%% Q15(8%)
%
% The ODE equation: dy/dx = 3x
% The initial value: y(-10) = -5
% The interval: [-10, 10]
% Requirements:
% 1. Write an anonymous function for the ODE
% 2. Apply the ode45 solver
% 3. Plot the numerical solution in blue color
% 2. Display the elapsed time for running your code.
%
% Write your code here:
func = @(X,Y)3*X;
interval=[-10 10];
y0=-5;
[x,y] = ode45(func,interval,y0);plot(x,y,’b-‘);
%% Optional question (6% extra credit)
% Write sybolic math expression to calculate the area of a circle with a
% radius r. You also want to substitute the symbolic variable r with a number,
% for example 5, and display the computed area’s real value in the Command
% Window.
syms r
area = r^2 *pi ;
subs(area, r, 5)
