Really easy one how to quickly repeat columns in an array

How do I repeat a column n times within an array to expand form 10x1 to 10x10?

e.g.
1
2
3
4
5
6
7
8
10

to

1 1 1 1 1 1 1 1 1 1 ;
2 2 2 2 2 2 2 2 2 2 ;
3 3 3 3 3 3 3 3 3 3 ;
4 4 4 4 4 4 4 4 4 4 ;
5 5 5 5 5 5 5 5 5 5 ;
6 6 6 6 6 6 6 6 6 6 ;
7 7 7 7 7 7 7 7 7 7 ;
8 8 8 8 8 8 8 8 8 8 ;
9 9 9 9 9 9 9 9 9 9 ;
10 10 10 10 10 10 10 10 10 10

Answer 1

[Jan]

Summary:

a = (1:1000).';
n = 1000;

tic;
for k = 1:1000
  M = repmat(a, 1, n);
end
toc    % 0.14 sec

tic;
for k = 1:1000
  M = repelem(a, 1, n);
end
toc    % 0.15 sec

tic;
for k = 1:1000
  M = a * ones(1, n);
end
toc    % 0.64 sec

tic;
for k = 1:1000
  M = a(:, ones(1, n));
end
toc    % 1.04 sec

tic;
for k = 1:1000
  M = kron(a, ones(1,n));
end
toc    % 0.19 sec

!!! Speed is checked in a Matlab online version - I expect it to be different on a local computer. Run it on your machine !!!

Answer 2

[per isakson]

C = (1:10)';
M = repmat( C, [1,10] );

inspect the result

>> whos C M
  Name       Size            Bytes  Class     Attributes
  C         10x1                80  double              
  M         10x10              800  double

Answer 3

[Andrei Bobrov]

a = 1:10;

out = a(:)*ones(1,10);

Answer 4

[Jan]

a = 1:10;
repelem(a.', 1, 10)

Answer 5

[Musa]

You can use the Kronecker tensor product

 a=1:10;
 kron(a',ones(1,10))