WEIRD ERROR (INDEX EXCEEDS MATRIX DIMENSIONS)

I am getting a weird error in the code, I am calling it weird becasue there's nothing wrong with the line of code where I am getting the error.

That line runs perfectly fine by itself. I am creating a matrix of zeros and then filling that matrix in a loop according to some conditions.

My code is below. Error on line 29, after the loop os run once!

%%%%CODE 
%channel overlap method
run_hours = 560;
cd('C:\Users\Abdul Wahab\Desktop\Topo_data')
topo_data = load('ZdataD_final.mat');
topo = topo_data.ZD;
nx = 796; %number of x points
ny = 522; % number of y points
deriv=zeros(nx,ny,run_hours-1);%creation of a matrix to store the elevation change information
% creation of a volume of 1s and 0s
for k =1:1:run_hours-1
    for i=1:1:nx
        for j=1:1:ny
          if(topo(i,j,k)-topo(i,j,k+1)>=1) || (topo(i,j,k)-topo(i,j,k+1)<=-1)
            deriv(i,j,k)=1;
          else
            deriv(i,j,k)=0;
          end
        end
    end
end
for k=1:1:run_hours-80
    perc_change = zeros(80,2,run_hours-80);
    for l=k:1:k+80
        deriv_t=zeros(nx,ny);
        for m=k:1:l
            for i=1:1:nx
                for j=1:1:ny
                    deriv_t(i,j)= deriv_t(i,j) + deriv(i,j,m);
                end
            end
        end
%         check_sum to assign all values greater than 1 to 1
        for i=1:1:nx
            for j=1:1:ny
                if(deriv_t(i,j)>=1)
                    deriv_t(i,j)=1;
                end
            end
        end
%         calcuate the percentage of delta change upto a given l
        ones=0;
        zeros=0;
        for i=1:1:nx
            for j=1:1:ny
                if(deriv_t(i,j)==1)
                    ones=ones+1;
                else
                    zeros=zeros+1;
                end
            end
        end
        perc_change(l-k+1,1,k)=l-k+1;
        perc_change(l-k+1,2,k)=ones/(ones+zeros);
    end
end

MathWorks

[Walter Roberson]

Can we have the data file for testing purposes?

Answer 1

[Niti K]

Try checking the limits on variable k in the second set of for loops.

k is defined from 1:run_hours-1 so deriv will have third dimension range from 1:559

From line 22 k will loop from 1:run_hours-80, however variable l(small L) in the for loop has a maximum range of run_hours(560). This is because of 'run_hours-80+80'

The for loop variable m is again dependent on k which will make deriv try to access 560th value in the third dimension. However deriv only has range up to 559.