Some basic MATLAB questions

165 次查看（过去 30 天）
Jonathon
Jonathon 2012-9-11
评论： Walter Roberson 2025-12-2，0:51
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
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) ;

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Matt Fig
Matt Fig 2012-9-11
编辑：Matt Fig 2012-9-11
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
nejib
nejib 2023-8-21
编辑：Walter Roberson 2025-12-2，0:45
Ran in:
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')
Walter Roberson
Walter Roberson 2025-12-2，0:51
Ran in:
@nejib
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')

请先登录，再进行评论。

更多回答（8 个）

Matt Tearle
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
Sean de Wolski 2012-9-11
+1: ordinal can behave like histc(). Learn something every day

请先登录，再进行评论。

Matt Fig
Matt Fig 2012-9-11
编辑：Matt Fig 2012-9-11
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'))
Matt Fig
Matt Fig 2012-9-11
编辑：Matt Fig 2012-9-11
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
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
显示 3更早的评论
Sean de Wolski
Sean de Wolski 2012-9-11
Inf and Nan are non supported. Converting them to reasonable values, strings are not supported.
Matt Fig
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...)

请先登录，再进行评论。

Jan
Jan 2012-9-11
index = max(1, ceil(-4.9:0.1:5.1));
pool = 'FDCBAA';
Grade = pool(index(x + 1));
Yash Meshram
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
hassan saher 2020-12-24
Use help command to get help about rand function.
Vivek Sharma
Vivek Sharma 2021-6-8
Please help me with the MATLAB code for the following problem. PDF is attached herewith.
Thank you.
  1 个评论
mahmood
mahmood 2023-5-17
编辑：DGM 2023-5-18
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);

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Numeric Types 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by