Matlab - Matriz de Combinacion progresiva

t=zeros(9,2);

a=[1:1:3];

b=[1:1:3];

t=combvec(a,b);

t=t';

t(:,[1 2])=t(:,[2 1])

t =

     1     1

     1     2

     1     3

     2     1

     2     2

     2     3

     3     1

     3     2

     3     3

clear all

a=round(20*rand)

v=[];

for i=1:a

    v=[v; i*ones(a,1)  [1:a]'];

end

v

>> matriz_combinacion_regresiva

a =

     2

v =

     1     1

     1     2

     2     1

     2     2

a =

     5

v =

     1     1

     1     2

     1     3

     1     4

     1     5

     2     1

     2     2

     2     3

     2     4

     2     5

     3     1

     3     2

     3     3

     3     4

     3     5

     4     1

     4     2

     4     3

     4     4

     4     5

     5     1

     5     2

     5     3

     5     4

     5     5