How to add rows containing zeros to a matrix

I have a "2x101" matrix, I want to add 4 rows to it, containing "zeros" to make it "6x101" matrix.

Please if anyone could guide me on syntax. Thankyou.

Answer 1

[Cris LaPierre]

A = rand(2,6)

A = 2×6

0.8131 0.2963 0.1224 0.8259 0.2399 0.5947 0.7303 0.1732 0.9839 0.2746 0.6453 0.7036

A(3:4,:)=0

A = 4×6

0.8131 0.2963 0.1224 0.8259 0.2399 0.5947 0.7303 0.1732 0.9839 0.2746 0.6453 0.7036 0 0 0 0 0 0 0 0 0 0 0 0

[Dr Sohaib Khan]

BiG FAT Thankyou :) Cris

Answer 2

[Voss]

Here's one way:

% a 2x101 matrix
a = rand(2,101)

a = 2×101

0.2749 0.6630 0.7375 0.2538 0.1755 0.5986 0.1725 0.4662 0.3609 0.7840 0.8763 0.3446 0.3603 0.8626 0.2283 0.1468 0.3254 0.3290 0.3960 0.4185 0.1099 0.0486 0.0626 0.7403 0.6850 0.4095 0.8703 0.1152 0.5754 0.7633 0.8014 0.8300 0.6248 0.5979 0.5868 0.4567 0.0246 0.0519 0.1590 0.1996 0.5126 0.0511 0.1397 0.9698 0.5512 0.3256 0.6557 0.6494 0.0743 0.7528 0.8313 0.6114 0.4597 0.6038 0.5030 0.9302 0.4747 0.8711 0.4699 0.2633

% append 4 rows of zeros
a = [a; zeros(4,size(a,2))]

a = 6×101

0.2749 0.6630 0.7375 0.2538 0.1755 0.5986 0.1725 0.4662 0.3609 0.7840 0.8763 0.3446 0.3603 0.8626 0.2283 0.1468 0.3254 0.3290 0.3960 0.4185 0.1099 0.0486 0.0626 0.7403 0.6850 0.4095 0.8703 0.1152 0.5754 0.7633 0.8014 0.8300 0.6248 0.5979 0.5868 0.4567 0.0246 0.0519 0.1590 0.1996 0.5126 0.0511 0.1397 0.9698 0.5512 0.3256 0.6557 0.6494 0.0743 0.7528 0.8313 0.6114 0.4597 0.6038 0.5030 0.9302 0.4747 0.8711 0.4699 0.2633 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

[Dr Sohaib Khan]

BiG FAT Thankyou :) Voss

Answer 3

[Les Beckham]

Here is another way.

A = rand(2,6)

A = 2×6

0.5677 0.5655 0.2207 0.5221 0.5033 0.0094 0.1184 0.9091 0.7727 0.4403 0.6020 0.3454

A(4,6) = 0

A = 4×6

0.5677 0.5655 0.2207 0.5221 0.5033 0.0094 0.1184 0.9091 0.7727 0.4403 0.6020 0.3454 0 0 0 0 0 0 0 0 0 0 0 0

[Dr Sohaib Khan]

BiG FAT Thankyou :) Beckham

Answer 4

[James Tursa]

E.g., one way using the end syntax:

my_matrix = reshape(1:12,3,4)

my_matrix = 3×4

1 4 7 10 2 5 8 11 3 6 9 12

n = 4; % number of rows to append
my_matrix(end+n,1) = 0

my_matrix = 7×4

1 4 7 10 2 5 8 11 3 6 9 12 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Basically, setting any element in the 4th row beyond the current last row will cause MATLAB to append 4 rows of 0's to the matrix and set the particular element. I.e., MATLAB will dynamically increase the size of the matrix to accomodate the element you are trying to set, and all of the elements you don't set in the process are automatically set to 0's. In the above example, I set the (7,1) element to 0 explicitly, and MATLAB filled in all the other elements in the newly created four rows to 0's automatically.

[Dr Sohaib Khan]

Understood Great Help :) James Thankyou :)