How to add zeros to the end of a column vector

I have two colum vectors that of uneven length that need to be added together as seen below:

a =

     1
     2
     3
     4
     5
     6
     7
     8
     9

b =

     1
     2
     3
     4
     5

How can I pad colum b from 5 onwards with zeros to allow the vectors to be added ?

Answer 1

[Dave B]

You can use padarray for this (or you can just do [b; zeros(numel(a)-numel(b),1)])

a = (1:9)'

a = 9×1

1 2 3 4 5 6 7 8 9

b = (1:5)'

b = 5×1

1 2 3 4 5

c=padarray(b,numel(a)-numel(b),0,'post')

c = 9×1

1 2 3 4 5 0 0 0 0

c2=[b; zeros(numel(a)-numel(b),1)] % alternate

c2 = 9×1

1 2 3 4 5 0 0 0 0

a+c

ans = 9×1

2 4 6 8 10 6 7 8 9

[Dave B]

you can even set the last value to zero and matlab will fill in the blanks:

a = (1:9)';
b = (1:5)';
b(numel(a)) = 0

b = 9×1

1 2 3 4 5 0 0 0 0

a+b

ans = 9×1

2 4 6 8 10 6 7 8 9

Answer 2

[Chien Poon]

b(length(b)+1:length(a)) = 0;

[Image Analyst]

Or more simply:

b(length(a)) = 0