Creating a matrix using for loop.

I am pretty new to matlab and I am trying create a matrix from a column vector.

The problem:

(This is a simplified version of my 100 x 1 vector and 100 x100 matrix.)

The column vector

a= [.12

   .1

   .2

   .3

   .4

   .5

   .6

   .7

   .8

   .9]

b= zeros(10,10)

I am trying to get

0 0 0 0 0 0 0 0 0 0

.12 0 0 0 0 0 0 0 0 0

.1 .12 0 0 0 0 0 0 0 0

.2 .1 .12 0 0 0 0 0 0 0

.3 .2 .1 .12 0 0 0 0 0 0

.4 .3 .2 .1 .12 0 0 0 0 0

.5 .4 .3 .2 .1 .12 0 0 0 0

.6 .5 .4 .3 .2 .1 .12 0 0 0

.7 .6 .5 .4 .3 .2 .1 .12 0 0

.8 .7 .6 .5 .4 .3 .2 .1 .12 0

.9 .8 .7 .6 .5 .4 .3 .2 .1 .12

is there a way to create a loop that will do this?

I have the start of a loop that will put the 1st value in the 1st column and the 2nd in the second column and so on and so forth. But everything I try, to get it to sort or shift does not get me the values in the places I need. I know I am missing something simple but I cant figure it out.

Thanks for the help! This is the start of the loop I have.

for i=1:100;

    f(i+1:100,i)=r(i);

%r is the 100 x 1 column all values are greater than zero less than 1

Answer 1

[C.J. Harris]

Try this:

a = [0.12;0.1;0.2;0.3;0.4;0.5;0.6;0.7;0.8;0.9]

f = zeros(length(a));

for b=length(a):-1:1
  f(:,length(a)+1-b) = [zeros(length(a)-b,1);a(1:b)];
end

Answer 2

[Andrei Bobrov]

b = [zeros(1,numel(a));tril(toeplitz(a))];

or

b = toeplitz([0;a],zeros(1,numel(a)));

or

a1  = [0;a];
i1 = (1:numel(a1))';
idx = bsxfun(@minus,i1,0:i1(end)-2);
idx(idx<=0)=1;
b = a1(idx);