matrix padding with zero

I have a 3x3 matrix and a 2x3 matrix. I need to pad zeros in the 2x3 matrix only at the bottom row such that it becomes 3x3.

If i have another matrix let's say 5x4 and second one 5x2, i need to pad the last 2 columns of the 5x2 matrix such that it has same rows and columns as 5x4.

a = [1,2,3; 3,2,1; 1,2,3];
b = [1,2,3; 3,2,1];
d = padarray(b,[1,0],0)

This code is padding a row above and a row below the matrix but i just want it below the 2x3 matrix.

[Anvinder]

In case if i have the second matrix always smaller than the first one then is there any ways by which it automatically gets padded as per the above mentioned criterion. It seems like i need to manually pad them based on the rows and columns of the second matrix every time.

[Image Analyst]

What is the second and what is the first? Please give examples with actual numbers of the two arrays and the final output array.

[Anvinder]

Hi, Apologize for the delayed response.

Here is the picture of the matrices i want to be padded in the given manner.

[Image Analyst]

Yep, my answer below will do it. Simply assign the lower right element to zero, even if that element does not exist yet, and it will pad everything up to there with zeros.

Answer 1

[Image Analyst]

Try this trick:

matrix2x2(3,3) = 0; % Add a row of zeros.

Then to turn the 5x2 into a 5x4:

b = rand(5,2)
array5x4 = padarray(b,[0,2],0, 'post')

[Anvinder]

If i write : a = [1,2,3; 3,2,1; 1,2,3]; b = [1,2,3; 3,2,1]; c = padarray(b,[0,2],0, 'post') then the input, output and padding it does is as per the shown figure attached but this is different from expected.