how to full fill the diagonal of a matrix by a vector

hello

how can i full fill a matrix (17*9) by a vector by length 9

for example i have the vector d=[1 2 3 ] and the matrix zeros(5*5) and i want to make the output matrix like this

1 0 0 3 2

2 1 0 0 3

3 2 1 0 0

0 3 2 1 0

0 0 3 2 1

thanks

Answer 1

[Adam Danz]

This approach uses circshift() to circularly shift the columns of matrix.

m = zeros(5,5); 
v = [1,2,3]; 

% Loop through each column of m
for i = 1:size(m,2)
    m(1:length(v),i) = v; 
    m(:,i) = circshift(m(:,1), i-1);
end

Result:

m =
     1     0     0     3     2
     2     1     0     0     3
     3     2     1     0     0
     0     3     2     1     0
     0     0     3     2     1

[Kamel]

thank you very much

[Adam Danz]

Glad I could help!

Answer 2

[Geoff Hayes]

Ahmed - try using

a = [1 2 3 0 0]';
A = cell2mat(arrayfun(@(x)circshift(a,x-1),1:length(a), 'UniformOutput', false));

We use arrayfun and circshift to apply an anonymous function that shifts the a down by one element (less one) for each of the five columns in your output matrix. We use cell2mat to conver the cell array output to a matrix.

[Adam Danz]

Nice! Simultaneous solutions with the same approach!

[Kamel]

ok, thank you

Answer 3

[Jan]

m = zeros(5,5); 
v = [1,2,3,4];
n = numel(v);
index = 1:n;
for i = 1:size(m,2)
    m(mod(i-1:i+n-2, 5)+1, i) = v; 
end

Answer 4

[Matt J]

You can use interpMatrix from the File Exchange

>> full(interpMatrix([1,2,3],1,5,1,'circ'))

ans =

     1     0     0     3     2
     2     1     0     0     3
     3     2     1     0     0
     0     3     2     1     0
     0     0     3     2     1