Thread Subject: Matrix : B (A)

Hi! If I have a matrix a= [ 10 11 12 13; 14 15 16 17];
and I want 2nd and 3rd element from each row so b=[2 3; 2
3];
is there a way to do a(b) to get [11 12; 15 16]; without
having to do it row by row?

Thanks,
S

In article <fno36i$pid$1@fred.mathworks.com>,
susan <suetibu@hotmail.com> wrote:
>Hi! If I have a matrix a= [ 10 11 12 13; 14 15 16 17];
>and I want 2nd and 3rd element from each row so b=[2 3; 2
>3];
>is there a way to do a(b) to get [11 12; 15 16]; without
>having to do it row by row?

a(:,[2 3])

If you need the indices to be derived from another variable
and that variable can be expressed as a single row, such as
b = [2 3]; then you can use a(:,b)

If you need the indices to be derived from another variable
and the variable cannot be expressed as a single row (perhaps
because you are extracting different elements from the different
rows) then you have a more complex task that will likely involve
sub2ind() at some point.
--
   "Beware of bugs in the above code; I have only proved it correct,
   not tried it." -- Donald Knuth

"susan " <suetibu@hotmail.com> wrote in message
<fno36i$pid$1@fred.mathworks.com>...
> Hi! If I have a matrix a= [ 10 11 12 13; 14 15 16 17];
> and I want 2nd and 3rd element from each row so b=[2 3; 2
> 3];
> is there a way to do a(b) to get [11 12; 15 16]; without
> having to do it row by row?
>
> Thanks,
> S


a= [ 10 11 12 13; 14 15 16 17];
b = 2:3 ;
a(:,b)

May I suggest to you to read the "Getting Started" section
of the (online) manual ...

hth
Jos