RE: Test of a pure function

*To*: mathgroup at smc.vnet.net*Subject*: [mg34038] RE: [mg34010] Test of a pure function*From*: "DrBob" <majort at cox-internet.com>*Date*: Sat, 27 Apr 2002 00:57:04 -0400 (EDT)*Reply-to*: <drbob at bigfoot.com>*Sender*: owner-wri-mathgroup at wolfram.com

A pure function isn't always the way to go --- for maintainability of the code, if nothing else. Look at this approach: xBins=Union[Sort[Random[Integer,{1,100}]&/@Range[10]]] {1,39,46,54,55,66,75,85,96,100} bracket[x_]:= Flatten[Position[ IntervalMemberQ[#,x]&/@ Interval/@ Transpose[{Join[{-\[Infinity]},xBins],Join[xBins,{\[Infinity]}]}], True]] bracket/@Join[{-20},xBins,{200}] {{1},{1,2},{2,3},{3,4},{4,5},{5,6},{6,7},{7,8},{8,9},{9,10},{10,11},{11} } This function gives the positions in xBins of elements that bracket x or, if x < Min[xBins] it gives {1}, and if x > Max[xBins] it gives {Length[xBins]+1}. The two special cases return singletons while usual cases result in at least two elements returned. It seems to me that a good solution might involve ListCorrelate, but I haven't been able to think that through as yet. Bobby Treat -----Original Message----- From: Shawn O'Connor [mailto:soconnor at ccs.nrl.navy.mil] To: mathgroup at smc.vnet.net Subject: [mg34038] [mg34010] Test of a pure function Hello, I hope someone can help me with this I know the solution should be easy but I am still learning how pure functions work. I am trying to pick out a position in a list were a number falls i.e. Position[xBins, _?(#1<=x <= #2 &)]. I keep getting errors Like these Function::slotn: Slot number 2 in #1¾x¾#2& cannot be filled from \ (#1¾x¾#2&)[List]. Function::slotn: Slot number 2 in #1¾x¾#2& cannot be filled from \ (#1¾x¾#2&)[-1]. From In[83]:= Function::slotn: Slot number 2 in #1¾x¾#2& cannot be filled from \ (#1¾x¾#2&)[-0.995]. General::stop: Further output of Function::slotn will be suppressed during \ this calculation. Can I make a comparison with the nth and nth+1 element in a pure function. Thank you,