how to use nested for loop by grabbing one column and subtracting another column.

so i have this huge file that is 1478 by 1236 matrix and i want to calculate the xslope and yslope as follows

[tonyrodriguez]

so far i have this

 cellsize = 9.47733915533982;
xslope = zeros(1478,1236);
n = length(xslope);

for i = 1:n for j = 1:1:n

        xslope(i,j) = ( z(i,j+1)-z(i,j)  )/cellsize;

    end
end
xslope

it tells me i have a matrix dismension.. can someone help me fix this or tell me how i can do it?

Answer 1

[Roger Stafford]

Your n value will be 1478, but in z(i,j+1) you have allowed the j+1 index to get as large as 1479 because you have "for j=1:1:n" and its maximum value should be only 1236. Hence the error message. You need to do

[n,m] = size(z)

and

for j = 1:m-1