How to increment and decrement within a vector in matlab

Question

Is there an easier way to create a such a vector b=[1,3,5,7,9,7,5,3,1]?

What I did was, I basically divided the vector into the increasing and decreasing parts and used horzcat as follows:

a=horzcat((1:2:9),(7:-2:1));

disp(a);

However, this doesn't seem very efficent. Is there a simpler way of doing this, without having to declare and concatanate two vectors?

Thanks.

Answer 1

It's not terribly inefficient, no. However, you don't need to call horzcat by name:

a = [1:2:9 7:-2:1]

But if you want to avoid the second set of colon operators, you could flip the first side:

a = 1:2:9;
a = [a fliplr(a(1:end-1))]

But there you have another colon, and it's definitely more efficient to do it the first way.

Possibly by c = 9; s = 2; b = 1:s:c-2; a = [b c fliplr(b)]; if c-1 is divisible by s, but I don't see the point of complicating a simple operation like this... unless this is how you get your kicks. ;)