How to add a constant value above a matrix in following code?

Hello

P is a matrix of 100 106 and I am trying to add 20 constant values (say 0.25) above each row and 20 constant values (say 0.21) below each rows to make P as 140 106. How I can change following code? instead of taking first value of each column (P(1,:)), how I can replace with a constant value?

A_pad = zeros(140,106);

A_pad(1:20,:) = ones(20,1)*P(1,:);

A_pad(21:120,:) = P;

A_pad(121:140,:) = ones(20,1)*P(end,:);

Answer 1

[Torsten]

P = [0.25*ones(20,106);P;0.21*ones(20,106)]

Answer 2

[Steven Lord]

A = magic(4)

A = 4×4

16 2 3 13 5 11 10 8 9 7 6 12 4 14 15 1

B = [repmat(-999, 2, width(A));
     A;
     repmat(Inf, 3, width(A))]

B = 9×4

-999 -999 -999 -999 -999 -999 -999 -999 16 2 3 13 5 11 10 8 9 7 6 12 4 14 15 1 Inf Inf Inf Inf Inf Inf Inf Inf Inf Inf Inf Inf

This pads 2 rows containing the constant -999 above the matrix A and 3 rows containing the constant Inf below.