Column vector with interval

Hi all, I'm looking for a way to create a column vector using something similar to "linspace". I saw that this is used to create ROW vectors with a starting point, an ending point and an interval (2,10,0.1). I should do a column vector for 2 to 0 with an interval of -0.1. Every time I try to do that I receive the "error (?)" Empty matrix: 1-by-0. How can I solve the problem? Is there a command as linspace for column row?

Answer 1

[W. Owen Brimijoin]

There are two ways to approach this and I think you're conflating the two:

Here's one option

colvec = [2:-.1:0]';

Here's the other:

colvec = linspace(2,0,21)';

Note that in the first example, you are specifying the interval (which must be negative) and this determines how many elements you end up with. In the second you are explicitly telling linspace how many elements you want (that's the 3rd argument for linspace) and this determines the interval between them.

In both cases the output is a row vector, so the transpose (') operator is used.

[AnnaMaria Accardo]

So, just to be sure, the (') means "transpose of the vector", right? As I said before, I'm new in matlab and I'm studying it

[W. Owen Brimijoin]

yes, putting that symbol in there will turn a row vector into a column, and vice versa. This works for matrices too, effectively rotating them by 90 degrees.

[AnnaMaria Accardo]

Perfect. Thanks. I'm sorry if the question was too stupid for you. I'm a very beginner student

[Jan]

@W. Owen Brimijoin: 2:-.1:0 is a vector already, such that additional square brackets are not required. But round parenthesis are needed for the transpose:

colvec = (2:-.1:0).';

[Jos (10584)]

@ W. Omen Brimijoin : Please note that transpose is not the same as rotating over 90 degrees ;-)

M = [1 2 3 ; 4 5 6]
rot90(M)
M.'

[Adam]

It's the same thing as a sensible 90-degree clockwise rotation rather than a Matlab counter-clockwise rotation!

[W. Owen Brimijoin]

Jan Simon, thank you, you are right that square brackets are not needed here! And Jos, rotation is a loaded word, for sure. In writing my response I had considered and discarded phrases like 'tipped upright,' 'flopped downward,' 'flipped down' and... oh I don't know... 'dangled down?'

The use of "rotation" seemed like a compromise between being intuitive and being correct. I still don't know what's best here!

best,

-Owen.

>

ps. Now I think I like being referred to as Omen Brimijoin. It has a certain dire ring to it.

Answer 2

[Azzi Abdelmalek]

v=2:-0.1:0
v=v'