How can I connect the points on my graph?

I have written code to plot graphs for the Hindmarsh-Rose equation, but, I have a few problems with it.

I can either plot the point for the graph inside the loop function, which is quick but the points are not connected. Or i can plot the points outside the loop function in which the points end up connected but to get the results it takes a long time.

I have tried a few different things like trying to store the values in an array so i can later use them in the code, but I assume I have not used them correctly as they dont work.

I wasn't sure what part of the code to add to help give a better picture so I decided to put it all in. Any suggestions would be appreciated.

a = 1.0;
b = 3.0;
c = 1.0;
d = 5.0;
I = 3.25;
r = 0.005;
s = 4.0;
p0 = -1.6;

dt = 1;
t = 0;
p = -1.6;
q = 4.0;
n = 2.75;

scale = 0.001;
ms = 50;
iterations = ms * 1000;

count = 0;
arrayp = zeros(1, ms);

for i = 0:iterations
    
    remainder = mod(i,1000); 
    
    if remainder == 0
        
        fprintf('t = %.4f  p = %.4f  q = %.4f  n = %.4f do = %.4f \n', t, p, q, n, do)
        
        arrayp(count, :) = (p);
        
        %Using this plot function works faster but the plots don't connect
        %plot(t,p, '-xr')
        %hold all
           
    end
    
    dp = q - (a*p.^3) + (b*p.^2) - n + I ;
    dq = c - (d*p.^2) - q;
    dn = r*(s*(p - p0) - n);
    
    p = p + (dp * scale);
    q = q + (dq * scale);
    n = n + (dn * scale);
    t = t + (dt * scale);
    
    %Using this plot function connects the points but it is slow
    %plot(t,p,'-xr')
    %hold all
          
end

Answer 1

[Adam Danz]

You need to store the values within the loop and then plot them after the loop.

The changes will look something like this incomplete example below. Importantly, i cannot start with 0 since you'll use it as an index.

t = nan(1,iterations);
p = nan(1,iterations);
t = 0;
p = -1.6;
for i = 2:iterations
    ...
    ...
    ...
    p(i) = p(i-1) + (dp * scale);
    ...
    t(i) = t(i-1) + (dt * scale);
end
plot(t,p,'-xr')

[Jonathan Dalby]

Thanks, this has helped a lot, had a few problems but i managed to figure it out and its working great.