Re: In which interval?

*To*: mathgroup at smc.vnet.net*Subject*: [mg13426] Re: [mg13303] In which interval?*From*: "Jurgen Tischer" <jtischer at col2.telecom.com.co>*Date*: Thu, 23 Jul 1998 03:33:28 -0400*Sender*: owner-wri-mathgroup at wolfram.com

Hi Pal, just for the fun of it I have still another solution: Say x is the vector of the x(i). Then define f=Interpolation[Transpose[{x,Range[0,Length[x]-1]}],InterpolationOrder->0] All you have to do afterwards is letting the guys of Wolfram Research do the work for you, f[R] will give the number of the interval. The only point to be careful about is if R is one of the x(i), my experiments are not conclusive on what will happen (as far as I can see, the upper point is counted as part of the interval in most cases). But this will be a problem with any method, because of the problem to decide was means equal, right? Jurgen -----Original Message----- From: Pal Lillevold <pal.lillevold at pensfins.no> To: mathgroup at smc.vnet.net Subject: [mg13426] [mg13303] In which interval? >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 >