Length of monotonic sequencies

*To*: mathgroup at smc.vnet.net*Subject*: [mg33579] Length of monotonic sequencies*From*: merkat <cabanc at hotmail.com>*Date*: Mon, 1 Apr 2002 02:02:13 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Hi I want to get the lengths of the monotonic rising and falling parts in a list l. for this I can use: Drop[RotateRight[l] - l, 1]; % /. x_ /; x > 0 -> 1 ; % /. x_ /; x < 0 -> -1 ; Split[%] Length /@ % I want to include the case of no change in the sequence values which makes the seqence longer. (flat progression) I further want to relax the condition of monotonicity by allowing shallow drops in the sequences. for a drop of one unit: { 2,3,2,3,4,3,5,3,4,3,7} gives {7,4} for a drop of 2 units: {2,3,4,2,5,6,5,1} gives {7,1} how can the code be written for an arbitrary drop? Merkat