How to make plot visible?

I have the following code

t1 = linspace(-15,15,10);
t2 = linspace(-15,15,1);
t3 = linspace(-15,15,.1);
x1 = 3*sin(2*pi*t1/10);
x2 = 3*sin(2*pi*t2/10);
x3 = 3*sin(2*pi*t3/10);
y1 = sin(2*pi*t1/20);
y2 = sin(2*pi*t2/20);
y3 = sin(2*pi*t3/20);

figure

subplot(3,2,1)
plot(t1,x1)
title('x(t)>>dt=10')

subplot(3,2,2)
plot(t2,x2)
title('x(t)>>dt=1')

subplot(3,2,3)
plot(t3,x3)
title('x(t)>>dt=.1')

subplot(3,2,4)
plot(t1,y1)
title('y(t)>>dt=10')

subplot(3,2,5)
plot(t2,y2)
title('y(t)>>dt=1')

subplot(3,2,6)
plot(t3,y3)
title('y(t)>>dt=.1')

clear

when plotted most of the graph dosent show up and i dont know why... can someone please give some input please, ill really appreciate any kind of help thank you

Answer 1

[Stephen23]

Problem You did not read the linspace documentation before using it. The linspace documentation says clearly: " y = linspace(x1,x2,n) generates n points."

Lets now see how you have used it:

t1 = linspace(-15,15,10);
t2 = linspace(-15,15,1);
t3 = linspace(-15,15,.1);

You have specified that the first generates ten points, the second one point, and the third zero points. And you then plot 10/1/0 points of data. You can try it yourself:

>> linspace(-15,15,10) % ten points
ans =
  -15.0000  -11.6667   -8.3333   -5.0000   -1.6667    1.6667    5.0000    8.3333   11.6667   15.0000
>> linspace(-15,15,1) % one point
ans =
    15
>> linspace(-15,15,0.1) % zero points
ans =
   Empty matrix: 1-by-0

And when you plot one point, or zero points: what do you expect to show up?

Solution

Read the documentation. Learn to try things and experiment. If you had actually looked at the sizes of t1, etc, then you could have figured out where the problem was.

For this code, use the colon operator:

>> -15:10:15
ans =
   -15    -5     5    15
>> -15:1:15
ans =
  Columns 1 through 23
   -15   -14   -13   -12   -11   -10    -9    -8    -7    -6    -5    -4    -3    -2    -1     0     1     2     3     4     5     6     7
  Columns 24 through 31
     8     9    10    11    12    13    14    15
>> -15:0.1:15
ans =
  Columns 1 through 13
  -15.0000  -14.9000  -14.8000  -14.7000  -14.6000  -14.5000  -14.4000  -14.3000  -14.2000  -14.1000  -14.0000  -13.9000  -13.8000
   ... lots here
  Columns 287 through 299
   13.6000   13.7000   13.8000   13.9000   14.0000   14.1000   14.2000   14.3000   14.4000   14.5000   14.6000   14.7000   14.8000
  Columns 300 through 301
   14.9000   15.0000

You also need to learn to get the computer to do your work for you: copy-and-pasting code is slow, inflexible, and buggy. Computers are good at repeating things lots of times, so just use a loop!:

V = [10,1,0.1]; % vector of step sizes
N = numel(V);
%
figure()
for k = 1:N
    T = -15:V(k):+15;
    X = 3*sin(2*pi*T/10);
    Y = sin(2*pi*T/20);
    % plot X
    subplot(3,2,2*(k-1)+1)
    plot(T,X)
    title(sprintf('x(t)>>dt=%g',V(k)))
    % plot Y
    subplot(3,2,2*(k-1)+2)
    plot(T,X)
    title(sprintf('y(t)>>dt=%g',V(k)))
end

which creates this plot:

Answer 2

[Star Strider]

If you actually put the clear call in your code, that could explain the reason nothing shows up.

From the documentation:

• clear removes all variables from the current workspace, releasing them from system memory.