For same Matrix subtraction between rows

I have matrix size (1508 x 19).

I want to do subtraction between rows like Row 1 - Row 2, Row 1 - Row 4, Row 1 - Row 6, Row 1 - Row 8, Row 1 - Row 10, Row 1 - Row 12, Row 1 - Row 14,

Row 1 - Row 16, Row 1 - Row 18.

without changing the size of a matrix and remainng rows like (row 1, 3, 5, 7, 9, 11, 13, 15, 17, 19) stay same in matrix.

Can some one help me please

Thank you in advance...

[João Mendes]

So what do you want as a result?

A matrix where the first row is row1-row2? The second one row1-row4? and so on?

What is your final goal?

Answer 1

[Asad (Mehrzad) Khoddam]

a(2:2:end,:) = a(1,:)-a(2:2:end,:);

[Vivek Shukla]

Can you help me more in this case?

I have matrix size (1508 x 19).

I want to do subtraction between rows like Row 3 - Row 5, Row 3 - Row 7, Row 3 - Row 9, Row 3 - Row 11, Row 3 - Row 13, Row 3 - Row 15, Row 3 - Row 17, Row 3 - Row 19.

without changing the size of a matrix and remainng rows like (row 1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18) stay same in matrix.

Can some one help me please

Thank you in advance...

[Asad (Mehrzad) Khoddam]

a(5:2:end,:) = a(3,:)-a(5:2:end,:);

[Vivek Shukla]

thank you