My matlab plot is not showing up anymore

Hi. I am plotting a graph, more specifically, the intensity of light against the points on a screen (a physics experiment). At first, my plot showed up with no problem, but after a while, my plot suddenly stopped showing up. There are no error numbers. Where my plot should be is now simply a grey, empty space. I searched for solutions and saw that people have had this problem before, but none of the solutions suggested have worked for me. Would anyone know why my plot is not showing up?

Here is some of my code:

clear all
clf
lambda = 700*10^-7;
a=-7;
b=0.1;
c=7;
distances_one = [];
first_intensity_vector = [];
for x = a:b:c
    l = 10;
    x3 = 10^-3;
    djx = sqrt((l^2)+(x-x3)^2);
    distances_one = [distances_one,djx];
    intensity_one = abs(exp((complex(0,1)*2*pi*djx)/lambda));
    first_intensity_vector = [first_intensity_vector, intensity_one];
end

(same thing for two, three, four and five)

    fiv = first_intensity_vector;
    siv = second_intensity_vector;
    tiv = third_intensity_vector;
    fuiv= fourth_intensity_vector;
    fiiv= fifth_intensity_vector;
    figure 
    tot_intensity_vector = fiv + siv + tiv + fuiv + fiiv 
    plot(tot_intensity_vector,screen_x_values, "r-")

Here is an image of how it looks:

Simply a grey, empty space where my plot should be.

I would appreciate help greatly.

Thank you at beforehand.

[Davide]

same thing here. I also tried with the most simple of plots, like:

x = 0:pi/100:2*pi;
y = sin(x);
plot(x,y)

but nothing is showing

Answer 1

[KALYAN ACHARJYA]

clear all
clf
lambda = 700*10^-7;
a = -7;
b = 0.1;
c = 7;
x_vals = a:b:c;  % Store x values, Is that x values 
distances_one = [];
first_intensity_vector = [];

for x = x_vals
    l = 10;
    x3 = 10^-3;
    djx = sqrt((l^2)+(x-x3)^2);
    distances_one = [distances_one,djx];
    intensity_one = abs(exp((complex(0,1)*2*pi*djx)/lambda));
    first_intensity_vector = [first_intensity_vector, intensity_one];
end

fiv = first_intensity_vector; % Change the data with real values
siv = first_intensity_vector;  % Change the data with real values
tiv = first_intensity_vector; % Change the data with real values
fuiv = first_intensity_vector;  % Change the data with real values

% Total intensity
tot_intensity_vector = fiv + siv + tiv + fuiv + fuiv;

figure;
plot(x_vals, tot_intensity_vector, 'r-');
xlabel('Screen Position (x)');
ylabel('Total Intensity');
grid on; 

Is that, are you looking for?

[Ellinor]

Yes, it is! May I please ask if you know why the code is working for you? I have the same code (except more code since I have code for intensity vector two, three and so on)?

Thank you!

Edit: now I see you changed second, third and so on to first.

[Ellinor]

and yes, I had my x-values on the y-axis, I understand it was confusing.

[KALYAN ACHARJYA]

Solved? @Ellinor

[Ellinor]

Well, I still don't really understand why my plot only shows a grey empty space. Maybe there is no answer to that. But yes, your code worked. I am just worried it will happen again soon. But thank you!

[KALYAN ACHARJYA]

The variables used in the code must be defined before they are referenced. The gray window appears due to the figure; function, but the rest of the code is not executable because the required variables () have not been defined.

siv = second_intensity_vector;
tiv = third_intensity_vector;
fuiv= fourth_intensity_vector;
fiiv= fifth_intensity_vector;

[Ellinor]

Hello. Thank you so much for your answer. However, I defined those variables in my code, I simply didn't post all my code, I only posted the code for the fifth intensity vector.