Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: Finding position in array
Replies: 10   Last Post: Jun 6, 2014 6:42 PM

 Messages: [ Previous | Next ]
 Helveticus Posts: 12 Registered: 11/3/13
Re: Finding position in array
Posted: Jun 6, 2014 4:06 AM

dpb <none@non.net> wrote in message <lmrh01\$m1u\$1@speranza.aioe.org>...
> On 6/5/2014 6:04 PM, Sepp wrote:
> > Hi
> >
> > I have an array of real numbers, let's say e.g.
> >
> > a = [1.23, 3.5, 6, 23.54, 44.234, 60.8];
> >
> > The array is sorted in ascending order.
> >
> > Now I have a new value, let's say 8.54 and I want to find the position
> > in the array a. The position would be after element 6 and before element
> > 23.54. I.e. I should somehow retrieve the index position 3
> > (corresponding to 6) or 4 (corresponding to 23.54).
> >
> > How can I do that efficiently in Matlab? I tried out the find method but
> > it doesn't work.

>
> Of course it works...
>

> >> a = [1.23, 3.5, 6, 23.54, 44.234, 60.8];
> >> x=8.54;
> >> find(x<a,1,'first')

> ans =
> 4

> >> find(x>a,1,'last')
> ans =
> 3

> >>
>
> --

Thank you very much. Both approaches works.

Date Subject Author
6/5/14 Helveticus
6/6/14 dpb
6/6/14 Helveticus
6/6/14 dpb
6/6/14 Bruno Luong
6/6/14 dpb
6/6/14 Bruno Luong
6/6/14 dpb
6/6/14 Bruno Luong
6/6/14 dpb
6/6/14 Bruno Luong