http://www.soton.ac.uk/~j...2-Ljubic-Traffic.pdf I would like to repeat this exercise ( shown in PDF above) using IDLs functionality on another dataset... Does anyone in this forum have a "point and shoot" app. for IDL for me to be able to "send it away" to group a CSV data set of 500 sequences of 100-300 time/value readings to sort them into groups based on common characterisitics of the curves that the time series plot out as (decreasing decelleration with time) A typical plot is shown on page 5 of this document: http://www.turnkey-instru.../gb/PDFs/SkidMan.pdf Regards John C Bullas TRG http://wwww.soton.ac.uk/~johnb/