MODULE absDiff0;
(*---------------------------------------------------------
File name: absDiff.pm
Author: AG
Date: 5/19/05 

Problem: This program computes the absolute difference on 
every element between two vectors of the same size.
Vectors are represented by chains. Then it computes the 
sum of all the differences.
In this example v1 is ID and v2 is all 1's
Sum( | v1[i] - v2[i] |)

Example of Execution:
	L1:  1  2  3  4  5  6  7  8  9 10 11 12 ...1000
	L2:  1  1  1  1  1  1  1  1  1  1  1  1  1  ... 1
	The sum of the absolute value of  L1 - L2 = 499500

Cycles:
1 substraction + 1 ABS + 1 REDUCE.
*)
(*----------------------------------------------------------
		CONFIGURATION
----------------------------------------------------------*)
CONST  MAXCELLS=1024; (* MAXCELLS cells in one line *)

CONFIGURATION chain[0..(MAXCELLS - 1)];
CONNECTION
		left: chain [i] -> chain[(i-1) MOD MAXCELLS];
		right: chain[i] -> chain[(i+1) MOD MAXCELLS];
(*----------------------------------------------------------
		VARIABLES
----------------------------------------------------------*)
VAR 
		L1, L2, L3: chain OF INTEGER;
		Res, RightLimit: INTEGER;
(*----------------------------------------------------------
		MAIN
----------------------------------------------------------*)
BEGIN
	(*initialize data *)
	RightLimit:= 1000;
	L1:= ID(chain);	(* L1 = 1 2 3 4 5 6.. *)
	L2:= 1;     		(* L2 = 1 1 1 1 1 1.. *)
	
	IF L1 <= RightLimit THEN
		L3:= L1-L2;	(*compute difference *)
		L3:= ABS(L3);	(*take absolute value *)
		Res:= REDUCE.SUM(L3);	(*sum of all *)
		
		(*printing*)
		WriteString("L1: "); WriteInt(L1, 2);WriteLn;
		WriteString("L2: "); WriteInt(L2, 2);WriteLn;
		WriteString(" The sum of the absolute value of  L1 - L2 = " );
		WriteInt(Res, 2);	(*Only prints the activated cells *)
	END; (*IF *)

END absDiff0.