My plot comes up as a white graph with no line.

When I try to plot with this code which is given below, nothing comes up. There are no errors, there's just a blank page. I want to lines between y values depending t values.

Please help me. Thank you from now.

clear all;
clc;
  for t=1:25
        
        if t==1,2,3,4,5;
            y(t) = 1
            
        elseif t==6,7,8,9,10;
                    y(t) = 0.9
        
            elseif t==11,12,13,14,15,;
                         y(t) = 1
                         
                elseif t==16,17,18,19,20,;
                         y(t) = 1.05
                    
                      elseif t==21,22,23,24,25,;
                         y(t) = 1
           
            end
  end
figure
hold on;plot(t, y)
xlabel('t(1/100)'); ylabel('VR'); 
title('VR Değişimi');

Expected graph is like that

Answer 1

[Stephen23]

The basic problem is that this syntax

if t==1,2,3,4,5;

is equivalent to writing this (i.e. each expression is evaluated independently):

 if t==1
    2
    3
    4
    5;

That is not the correct way to compare mulitple values at once. Remember that the name MATLAB comes from MATrix LABoratory: you should always keep your data in vectors/matrices/arrays. For example:

if any(t==[1,2,3,4,5])
%         ^^^^^^^^^^^ vector!

Note that you should preallocate y before the loop:

https://www.mathworks.com/help/matlab/matlab_prog/preallocating-arrays.html

Note that whilst it is certainly possible to plot vertical lines, your approach will not do this.

[Stephen23]

"How can I make non-vertical lines vertical?"

You need to think about both end points of the vertical line:

X = [0,1,1,2];
Y = [0.1,0.1,0.9,0.9];
plot(X,Y,'-*')
ylim([0,1])

[Yunus Mercan]

Thank you Stephen Cobeldick , it worked.

[Image Analyst]

Instead of an if/else, a switch statement can be used to compare multiple cases at a time. For example:

switch(result)
   case 1
      disp('result is 1')
   case {52, 78}
      disp('result is 52 or 78')
end

Answer 2

[Atsushi Ueno]

1. After exexuting your script, y is like [1 0 0 0 0 0.9 0 0 0 0 1 ....] it must be different from what you expected.
2. After executinf for loop, the variable t is going to be deleted. So, you need t = 1:25 after the for loop.

How about the code below?

clear all;
clc;
t = 1:25;
y = repelem([1 0.9 1 1.05 1], 1, 5);
figure
hold on;
plot(t, y)
xlabel('t(1/100)');
ylabel('VR'); 
title('VR Değişimi');

[Yunus Mercan]

Dear Atsushi Ueno, Firstly, thank you. Your code creates graph given below. How can I make non-vertical lines vertical? I mean, at t=5 VR=0.9 not t=6. Same way at other points. Thank you so much again.

[Atsushi Ueno]

How about using stem(t, y) or stairs(t, y) instead of plot(t, y)?

You have to care about index for using other functions.

clear all;
clc;
t = 0:24; % just changed from 1:25 for stairs()
y = repelem([1 0.9 1 1.05 1], 1, 5);
figure
hold on;
stairs(t, y);
xlabel('t(1/100)');
ylabel('VR'); 
title('VR Değişimi');

[Yunus Mercan]

Atsushi Ueno,It works fine this time, thank you for your interest.

Answer 3

[Jithin Nambiar J]

Your code can get pretty long and tedious. The if statement in your code would not work well because it wont compare the values separated by commas properly.

t=0.0001:0.01:40;
x=[t>0]-0.05.*[t>5]+0.05.*[t>15]+0.05.*[t>25]-0.05.*[t>35];
plot(t,x)
grid on;
xlabel('t(1/100)'); ylabel('VR'); 
title('VR Değişimi');

Unless you plan to plot another graph in the same above plot. You don't need to use

hold on

Hope this helps. Cheers!

[Yunus Mercan]

Thank you Jithin Nambiar J,It works fine.