Re: How to find the kinks in a list

*To*: mathgroup at smc.vnet.net*Subject*: [mg104380] Re: How to find the kinks in a list*From*: ADL <alberto.dilullo at tiscali.it>*Date*: Thu, 29 Oct 2009 03:00:01 -0500 (EST)*References*: <hc91oo$e4g$1@smc.vnet.net>

This might work: data = ImportString["... your data ...", "Table"]; {x, y} = Transpose[data]; (*finds the x corresponding to maximum y*) maxPos[xli_?VectorQ, yli_?VectorQ] := xli[[Flatten[Position[yli, Max [yli]]]]]; (*finds the x corresponding to minimum y*) minPos[xli_?VectorQ, yli_?VectorQ] := xli[[Flatten[Position[yli, Min [yli]]]]]; (*computes a balanced derivative*) dd[x_] := ListCorrelate[Join[{-1}, Table[0, {1}], {1}]/2, x]; (*computes a 3-moving average*) mm[x_] := MovingAverage[x, 3]; (*computes the second derivative*) ddx = mm@mm@x; ddy = dd@dd@y; maxPos[ddx, ddy] ==> {1.51} minPos[ddx, ddy] ==> {3.31} ADL On Oct 28, 10:09 am, Mather <sdzbb... at hotmail.com> wrote: > Hi, all > > I want to get the two kinks in the following list, say, x=1.5 and 3.3 > by Mathematica. > However I have no idea which command to employ. > Can anyone help? Thanks in advance! > ...