randomising a given matrics

hello there i need to randomize a matrix and after that i need to get it back original matrix ... can any one help me

[Jan]

Please explain, what "randomize" and "get back" mean. Do you want to add a random matrix, or sort the rows and/or columns randomly and store the sorting index? A small example might be helpful also.

It is always a good idea to read an own question again and trying to imagine, if a foreign reader has enough information to understand the computational part of the problem. without understanding the problem, a meaningful answer is not possible.

[sumit choubey]

thanx for replying

actually i want to swap the element of a given matrix and and then after than i want to get it back in original matrix

for e.g.

a=[1 3 4;5 6 7]

i want to swap its element to get for e.g [1 4 6;3 7 5]

then i want again the original matrix a=[1 3 4;5 6 7]

Answer 1

[Grzegorz Knor]

I'll try to answer :)

% test matrix
a = reshape(1:100,10,10)
% randomize - mixing
idx = reshape(randperm(numel(a)),10,10);
b = a(idx)

[~ c] = sort(idx(:));
% restore matrix a
b = b(reshape(c,10,10))

[sumit choubey]

thanx but its not working

[Andrei Bobrov]

use

[~, c] = sort(idx(:));

or

[non,c] = sort(idx(:));

[Grzegorz Knor]

What is wrong?

Can you paste an error?

Try replace the line:

[~ c] = sort(idx(:));

with:

[ignore, c] = sort(idx(:));

[Andrei Bobrov]

Hi Grzegorz!

% test matrix

a = reshape(1:100,10,10)

% randomize - mixing

b = a;

idx = randperm(numel(a));

b(:) = a(idx)

[~, c] = sort(idx(:));

% restore matrix a

b(:) = b(c)

[sumit choubey]

??? Error: File: randomising1.m Line: 7 Column: 2

An array for multiple LHS assignment cannot contain expressions.

??? Error: File: randomising1.m Line: 7 Column: 2

An array for multiple LHS assignment cannot contain expressions.

[sumit choubey]

this was the error message

[sumit choubey]

thanx it seems to be working .....let me check on my problem ...thanx a lot...

[sumit choubey]

replacing [~c]with[~,c] is working thanx