# 99x99 matrix

8 views (last 30 days)
Luke chin on 15 Oct 2021
Answered: Chunru on 15 Oct 2021
create a 99x99 matrix with ones on both diagonals and zeros everywhere otherwise

Image Analyst on 15 Oct 2021
Another way, even more compact:
A = eye(99) | fliplr(eye(99))
As long as it's not your homework you can use my code.
Chetan Bhavsar on 15 Oct 2021
great wayorring flip i liked it

Chunru on 15 Oct 2021
n = 9; %99
A = eye(n);
A(n:n-1:n*n-1) = 1; % anti-diagonal
A
A = 9×9
1 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 1

Image Analyst on 15 Oct 2021
As long as it's not your homework you can use my code:
A = min(1, eye(99) + fliplr(eye(99)))

Chunru on 15 Oct 2021
% For time comparison:
n = 1000;
timeit(@() bidiag1(n))
ans = 4.1086e-04
timeit(@() bidiag2(n))
ans = 0.0027
timeit(@() bidiag3(n))
ans = 0.0019
function bidiag1(n)
a = eye(n);
a(n:n-1:n*n-1) = 1;
end
function bidiag2(n)
a = eye(n) | fliplr(eye(n));
end
function bidiag3(n)
a = min(1, eye(n) + fliplr(eye(n)));
end