Filtered signal plot not showing up

I'm attempting to filter a certain portion of data from an external file using a moving average for a hw problem, and having trouble figuring out exactly what is wrong. I have no errors when I run the code, but my second plot doesn't show up.

clear all

load raw_data.mat

n = 200;

filter(500:700) = signal(500:700);

for k = 500:(n-1)
    mean_w_curr = (signal(k-2) + signal(k-1) + signal(k) + signal(k+1) + signal(k+2))/5
    mean_wo_curr = (signal(k-2) + signal(k-1) + signal(k+1) + signal(k+2))/4
    
    if abs(mean_w_curr(k) - mean_wo_curr(k)) > .001
        filter(k) = mean_wo_curr(k)
    
    else
        filter(k) = signal(k)
    end    
end

plot(500:700, signal(500:700),'r')

hold on

plot(filter(k),'b')

Answer 1

[Star Strider]

It’s necessary for you to understand the problem with your indexing.

This:

n = 200;
k = 500:(n-1)

produces:

k =
  1×0 empty double row vector

Since this is homework, I’m porviding you with this link to the documentation on the colon operator to understand the reaons this is not working.