Problem 1704. Triangular matrices in 3D array

Solution 1421932

Submitted on 22 Jan 2018 by Andrew Dobrovolc

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Test	Status	Code Input and Output
1	Pass	x(:,:,1) = [1 2 3;4 5 6;7 8 9]; x(:,:,2) = [1 4 7;2 5 8;3 6 9]; x(:,:,3) = [1 2 3;1 2 3;1 2 3]; y_correct(:,:,1) = [1 0 0;4 5 0;7 8 9]; y_correct(:,:,2) = [1 0 0;2 5 0;3 6 9]; y_correct(:,:,3) = [1 0 0;1 2 0;1 2 3]; assert(isequal(tril3(x),y_correct))
2	Pass	x = cumsum(ones(3,3,50)); y_correct = repmat([1 0 0;2 2 0; 3 3 3],[1,1,50]); assert(isequal(tril3(x),y_correct))
3	Pass	x = cumsum(ones(5,5,100),2); y_correct = repmat(tril(cumsum(ones(5,5),2)),[1,1,100]); assert(isequal(tril3(x),y_correct))
4	Pass	x = rand([1 1 400]); y_correct = x; assert(isequal(tril3(x),y_correct))
5	Pass	x = reshape(1:40,[2,2,10]); y_correct(:,:,1) = [1 0;2 4]; y_correct(:,:,2) = [5 0;6 8]; y_correct(:,:,3) = [9 0;10 12]; y_correct(:,:,4) = [13 0;14 16]; y_correct(:,:,5) = [17 0;18 20]; y_correct(:,:,6) = [21 0;22 24]; y_correct(:,:,7) = [25 0;26 28]; y_correct(:,:,8) = [29 0;30 32]; y_correct(:,:,9) = [33 0;34 36]; y_correct(:,:,10) = [37 0;38 40]; assert(isequal(tril3(x),y_correct))
6	Pass	x = randi([0 1],[4,4,5]); y_correct(:,:,1) = tril(x(:,:,1)); y_correct(:,:,2) = tril(x(:,:,2)); y_correct(:,:,3) = tril(x(:,:,3)); y_correct(:,:,4) = tril(x(:,:,4)); y_correct(:,:,5) = tril(x(:,:,5)); assert(isequal(tril3(x),y_correct))