triangle matrix with different number of columns

how to make a triangle matrix, from a matrix example like this

a =

     35     1     6    26    19    24
     3    32     7    21    23    25
    31     9     2    22    27    20
     8    28    33    17    10    15
    30     5    34    12    14    16
     4    36    29    13    18    11

and the matrix that i'm looking for will like this a =

    35     1     6    26    19    24
     0    32     7    21    23    0 
     0    0      2    22    0     0

 Thanks, Rio

[Azzi Abdelmalek]

Your result is not a matrix

[rio hartanto]

oke edited, can you help me now?

Answer 1

[Guillaume]

Use triu (or tril to get triangular matrices. Use flipr on the matrix and on the output, if you want to apply them antidiagonally (which is an odd thing to want):

a = [ 35     1     6    26    19    24
       3    32     7    21    23    25
      31     9     2    22    27    20
       8    28    33    17    10    15
      30     5    34    12    14    16
       4    36    29    13    18    11];
out = fliplr(triu(fliplr(triu(a(1:3, :)))))

[rio hartanto]

Ok thanks man, it's really solved