Change of sign in a matrix one by one

Hi to all the users. I have a matrix A = ones(5), I want to change the sign of elements one by one but under the condition with rand(1).

Pick random position 1 in A then take rand_number = rand(1) if rand_number>=0.5 fix that 1 to -1

else 1 remains 1 then again pick 1 from the remaining 1s in the matrix A continue till all ones go to -1

Hope i have explained well.

Regards

Answer 1

[KSSV]

A = ones(5) ;
Ac = A(:) ;
pos = 1:length(Ac) ;
for i = 1:length(pos)
    rand_pos = randsample(pos,1) ;
    if rand(1) > 0.5
        Ac(rand_pos) = -1 ;
    end
    pos = setdiff(pos,rand_pos) ;
end
A = reshape(Ac,5,5) ;

[Offroad Jeep]

Thanks for your concern........ but the all the ones are not changing to -1 the loop stops

[KSSV]

Your condition was if rand(1) > 0.5 then change 1 to -1.

[KSSV]

A = ones(5) ;
Ac = A(:) ;
pos = 1:length(Ac) ;
while ~isempty(pos)
    rand_pos = randsample(pos,1) ;
    if rand(1) > 0.5
        Ac(rand_pos) = -1 ;
         pos = setdiff(pos,rand_pos)  ;
    end
end

A = reshape(Ac,5,5) ;