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

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dpb

Posts: 8,181
Registered: 6/7/07
Re: Finding position in array
Posted: Jun 6, 2014 12:44 AM
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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
>>

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