how velocize it? (vectorize it)

 a=magic(8)

a = 8×8

64 2 3 61 60 6 7 57 9 55 54 12 13 51 50 16 17 47 46 20 21 43 42 24 40 26 27 37 36 30 31 33 32 34 35 29 28 38 39 25 41 23 22 44 45 19 18 48 49 15 14 52 53 11 10 56 8 58 59 5 4 62 63 1

 b=[1 3 2 4 5 5 8 3] %  (b is always >0)

b = 1×8

1 3 2 4 5 5 8 3

[~,c]=size(a);

B=a;

for i=1:c
    if b(i)>1
      B(1:b(i)-1,i)=0;
    end

end    

B

B = 8×8

64 0 0 0 0 0 0 0 9 0 54 0 0 0 0 0 17 47 46 0 0 0 0 24 40 26 27 37 0 0 0 33 32 34 35 29 28 38 0 25 41 23 22 44 45 19 0 48 49 15 14 52 53 11 0 56 8 58 59 5 4 62 63 1

Answer 1

[Bruno Luong]

a=magic(8)

a = 8×8

64 2 3 61 60 6 7 57 9 55 54 12 13 51 50 16 17 47 46 20 21 43 42 24 40 26 27 37 36 30 31 33 32 34 35 29 28 38 39 25 41 23 22 44 45 19 18 48 49 15 14 52 53 11 10 56 8 58 59 5 4 62 63 1

b=[1 3 2 4 5 5 8 3] %  (b is always >0)

b = 1×8

1 3 2 4 5 5 8 3

B = a.* ((1:size(a,1))' >= b)

B = 8×8

64 0 0 0 0 0 0 0 9 0 54 0 0 0 0 0 17 47 46 0 0 0 0 24 40 26 27 37 0 0 0 33 32 34 35 29 28 38 0 25 41 23 22 44 45 19 0 48 49 15 14 52 53 11 0 56 8 58 59 5 4 62 63 1

[aldo]

thank you.!!!