I have the matrix (which is basically the matrix representation of several lines)
A = [10 5 10
0 4 3
2 0 8
0 6 5];
I want to find the intersection between the lines starting from bottom going up (for each column seperately) when the gradients are non-zero, e.g., the last row of first column has zero gradient so I ignore it and move up to third row, but the second row has zero gradient as well, so I calculate its intersection with the first row:
The first row elements are always non-zero and since there is no "previous row" before the first row, the intersection of the those lines by default are set to zero. I have achieved my target using for loop, but I was hoping to avoid for loops if possible (I will have more columns than just 3). Here is what I have done:
for k = 1:2
B = A(A(1:end,k)~=0,[k,n]);
[r,~] = size(B);
c = 2:r;
if isempty(c)
x{k} = 0;
else
x{k} = [0; (B(c,end)-B(c-1,end))./(B(c-1,1)-B(c,1))];
end
end
which gives me my desired results:
>> x{1}
ans =
0
-0.2500
>> x{2}
ans =
0
-7
-1
Notice how the dimensions of x{1} and x{2} are different, and thus I had to use curly brackets. Avoiding the for loop can save me great deal of computational time. Thanks in advance! Let me know if you have any question.
