In the MATLAB, a matrix cell is numbered by its row and column position. I wanted to index by the integer number.
Consider a (3,4) matrix
for i=1:length(3)
for j =1:length(4)
fprint(i,j)
end
end
1,1
1,2
.
.
3,4
However, the output I am expecting when iterating through each cell is given by
for i=1:length(3)
for j =1:length(4)
fprint(i+j+something)
end
end
1
2
3
4
.
.
12
This is called linear indexing. You can use the function sub2ind to convert from row and column number to linear index, and ind2sub to go the other way.
index = sub2ind(size(M),i,j);
M(i,j) == M(index)
The formula applied by sub2ind for a 2D matrix is index = i + (j-1) * size(M,1). That is, numbers increase downward along the first column, then the second column, etc.
for i=1:length(3) for j=1:length(3) n = sub2ind(size(Rld),i,j); fprintf('%i\n',n) end end For unknown reasons , it prints only 1, not 1..9. Any idea what could be wrong here.
length(3) is 1. You want to do for i=1:3.
index = i + (j - 1) * size(M,1)