change a value in matrix

A=[1,0,5,3,0;2,0,6,0,9;0,0,5,3,1];
idx = randperm(size(A,1),1);
[~,col,val]=find(A(idx,:)); 
changed=val+0.5*rand;

I want to make a new_A according to changed value. if

idx=2, changed=[2.11,6.11,9.11];

new_A should be

new_A=[1,0,5,3,0;2.11,0,6.11,0,9.11;0,0,5,3,1];

Answer 1

[Guillaume]

Note that

idx = randi(size(A, 1));

would make more sense than randperm with just one element output. Anyway,

randomrow = randi(size(A, 1));  %better name than idx as well.
A(randomrow, :) = A(randomrow, :) + 0.5 * rand * (A(randomrow, :) ~= 0)