Some basic MATLAB questions
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Okay, so I'm just starting to use MATLAB for engineering assignments. The assignment from my instructor requires us to write a loop using if, else if and else commands. Thats not what I have trouble with, but I need some assistance to come up with a way to take a number and assign it a letter grade based on the number. So the grading scale is like this:
0-59 - F 60-69 - D 70-79 - C 80-89 - B 90-100 - A
So I know I will start the first condition with if, but could someone do an example to show me how it is supposed to be set up? Please DO NOT do the whole thing, as I want to learn it on my own, but sometimes we need a bit of assistance.
Thank you
EDIT: Thanks to Matt for the first Question.
1 个评论
Naftali
2013-2-18
编辑：Walter Roberson
2013-2-18
% n - input numbers in array
% g - output grades
grades = 'FDCBA' ;
k = min(max(floor(0.1*(n-50)+1,1),5) ;
g = grades(k) ;
采纳的回答
X = round(rand*6)
if X<3
disp('Small X')
elseif X==3
disp('X is 3')
elseif X>=3 & X<5
disp('Medium X')
else
disp('X is 5 or 6')
end
2 个评论
hello :
i need to have the the same amplitude!!!!
any help : !!
t = 0:1/1e3:10;
d = [0:2:60;sin(1*pi*0.1*(0:2:60))]';
x = @rectpuls;
y = pulstran(t,d,x);
plot(t,y)
hold off
xlabel('Time (s)')
ylabel('Waveform')
Same amplitude:
t = 0:1/1e3:10;
d = 0:2:60;
x = @rectpuls;
y = pulstran(t,d,x);
plot(t,y)
hold off
xlabel('Time (s)')
ylabel('Waveform')
更多回答（8 个）
Matt Tearle
2012-9-11
Thank you for your asking such a great question! Matt has basically given you all the info you need for this assignment, but, in the spirit of Sean's "not what you were asked, but some cool stuff you should know about MATLAB"...
x = randi(100,20,1) % Make some grades
y = char(70*ones(size(x))); % Everyone gets an F!
y(x>59) = 'D' % Upgrade the Ds (and better)
y(x>69) = 'C' % Upgrade the Cs
y(x>79) = 'B' % The Bs
y(x>89) = 'A' % And finally the As
Or (requires Stats TB, which you should have as a student)
y = ordinal(x,{'F','D','C','B','A'},[],[0,60:10:100])
hist(y) % See the grades
pie(hist(y)) % Grade distribution
mean(x(y>='C')) % The average score of those who got a C or better
1 个评论
Sean de Wolski
2012-9-11
+1: ordinal can behave like histc(). Learn something every day
As per requested:
% x is the numerical unknown grade
G = char(interp1([-inf,59,60,69,70,79,80,89,90,inf],['FFDDCCBBAA'],x,'n'))
or, for 2012+ versions:
G = char(interp1([-realmax,59,60,69,70,79,80,89,90,realmax],double(['FFDDCCBBAA']),x,'n'))
Another one-liner (short!):
% x is the unknown numerical grade.
G = char(65+sum(x<.5+[59 59:10:89]));
As it stands it only works for scalar x. BSXFUN would cure that if it was needed, like so.
G = char(65+sum(bsxfun(@lt,x,.5+[59 59:10:89].')));
Sean de Wolski
2012-9-11
编辑：Sean de Wolski
2012-9-11
I know this is not the purpose of your assignment, but here is a cool way to do it. The logic should be easily transmittable to if/else/etc instead of histc()
letters = 'FDCBA';
grade = 87
[~,idx] = histc(grade,[0 59:10:89 100+eps(100)]);
letters(idx)
5 个评论
I like this one too!
char(interp1([-inf,59,60,69,70,79,80,89,90,inf],['FFDDCCBBAA'],87,'n'))
Sean de Wolski
2012-9-11
I like it! Interestingly though, this no longer works in 12a.
Hump-day challenger tomorrow?
What is the error message in R2012a? But this does still work, I hope:
char(interp1([-inf,59,60,69,70,79,80,89,90,inf], double('FFDDCCBBAA'), 87, 'n'))
Please, Matt Fig, post your one-lines as an answer.
Sean de Wolski
2012-9-11
Inf and Nan are non supported. Converting them to reasonable values, strings are not supported.
Matt Fig
2012-9-11
Now why would support for inf be dropped? TMW does some strange stuff from time to time. (strmatch, findstr, etc...)
Jan
2012-9-11
index = max(1, ceil(-4.9:0.1:5.1));
pool = 'FDCBAA';
Grade = pool(index(x + 1));
Yash Meshram
2019-10-24
i = input('Marks of the student: ');
if 0<=i && i<=59
fprintf('F grade\n');
end
if 60<=i && i<=69
fprintf('D grade\n');
end
if 70<=i && i<=79
fprintf('C grade\n');
end
if 80<=i && i<=89
fprintf('B grade\n');
end
if 90<=i && i<=100
fprintf('A grade\n');
end
hassan saher
2020-12-24
0 个投票
Use help command to get help about rand function.
Vivek Sharma
2021-6-8
0 个投票
Please help me with the MATLAB code for the following problem. PDF is attached herewith.
Thank you.
1 个评论
clc;
clear;
% Constants
c = 13.03;
p = 19.93;
% Initial temperatures
T1 = 576;
T2 = 439;
% Number of impacts
m = 5;
% Initialize variables
T = (T1 + T2) / 2;
E = zeros(m, 1);
% Perform m impacts
for i = 1:m
E(i) = (c * p * T) / 23.5;
T = (T1 + T) / 2;
end
% Display the values of E for each impact
disp('Values of E for each impact:');
disp(E);
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