Creating certain amount of new rows from each row in a matrix?

How can I create certain amount of rows from each row? For example

A=[a b c d

Then I want to create n new rows from the first row, and m new rows from the second and third row.

     e f g h
     i j k l]

from [a b c d] => Let n=2 =>

                             New rows [x y z k
                                       t y j m]

[Azzi Abdelmalek]

How x,y,... are related to a,b,...?

[CarenCaren]

New_one = firstrow ± (rand()/intensity) ×  firstrow
New_one = secondrow ± rand() × secondrow

Answer 1

[Walter Roberson]

[repmat(A(1,:), n, 1);
 repmat(A(2:end,:), m, 1)]

[Walter Roberson]

A1_n = repmat(A(1,:), n, 1);
A2_m = repmat(A(2,:), m, 1);
A3_m = repmat(A(3,:), m, 1);
Acol = size(A,2);

result = [A1_n + repmat((rand(n,1) * 2 - 1) / intensity, 1, Acol) .* A1_n;
          A2_m + repmat(rand(m, 1) * 2 - 1, 1, Acol) .* A2_m;
          A3_m + repmat(rand(m, 1) * 2 - 1, 1, Acol) .* A3_m];

[CarenCaren]

Thanks a lot.