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Re: In which interval?

  • To: mathgroup at
  • Subject: [mg13361] Re: In which interval?
  • From: "Allan Hayes" <hay at>
  • Date: Mon, 20 Jul 1998 02:50:14 -0400
  • References: <6oklgc$>
  • Sender: owner-wri-mathgroup at

Pal Lillevold wrote in message <6oklgc$1nq at>...
>I need to resolve the following problem:
>Given N distinct real Intervals (x(i),x(i+1)); i=1,,,,N and a real
>number R - in which interval is R located. In other words to identify
>the unique value of i such that x(i)<=R<x(i+1). This is easy to do by
>straight forward checking which value of the N i's which match the
>inequalities. But this is very time-consuming when the number N is
>large. Has anyone been confronted with this problem and resolved it
>efficiently? I would highly appreciate any assistance.
>Thank you in advance and best regards.
>Pal Lillevold


pts = {1,2,4,6,10};

pts[[Flatten[{#-1,#}]&[Position[pts, x_/;(3<x),{1},1, Heads->False]]]]


Allan Hayes
Training and Consulting
Leicester UK
hay at
voice: +44 (0)116 271 4198
fax: +44(0)116 271 8642

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