I have a large matrix let's say A 150 * 220000 , including columns that are set entirely to zero .
I want to find '' column wise'' the first element that is larger than 5 and the first element smaller than 200 and store them as two vectors
I creat a for loop, but it breaks when it reaches the first zero column in the matrix. so instead of idx_start 1 * 220000 , I get idx_start 1 * 15000
how can i modify my code so the loop continue over the zero columns?
and would be better if I replaced the zero columns with NaN?
I tried something with isempty but it does not work like I want.
wenn the condition is not met, it is enough to be replaced with NaN
[nx,ny] = size(A) ;
for j = 1:ny
idx_start(:,j) = find(A(:,j)> 5 ,1,'first') ;
idx_end(:,j) = find (A(:,j) < 200 , 1, 'first');