michael@0: # This Source Code Form is subject to the terms of the Mozilla Public
michael@0: # License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0: # file, You can obtain one at http://mozilla.org/MPL/2.0/.
michael@0: 
michael@0: function regress(DATAPOINTS,SX,SY,SXY,SX2)
michael@0: {
michael@0:    b1 = (DATAPOINTS * SXY - SX * SY) / (DATAPOINTS * SX2 - SX * SX);
michael@0:    b0 = (SY - b1 * SX ) / DATAPOINTS;
michael@0:    return b1 " * x + " b0; 
michael@0: }
michael@0: 
michael@0: BEGIN {
michael@0:         if (!Skip) Skip = 0;
michael@0:         if (Interval) 
michael@0:         {
michael@0:            Count = 0;
michael@0:            IntervalCount = 0;
michael@0:         }
michael@0:       }
michael@0: 
michael@0: NR>Skip {
michael@0:         sx += $1;
michael@0:         sy += $2;
michael@0:         sxy += $1 * $2;
michael@0:         sx2 += $1 * $1;
michael@0:         #print NR " " sx " " sy " " sxy " " sx2
michael@0: 
michael@0:         if (Interval)
michael@0:         {
michael@0:            if(Count == Interval-1)
michael@0:            {
michael@0:               IntervalCount += 1;
michael@0: 
michael@0:               print NR-Count, "-", NR, ":  ", regress(Count,isx,isy,isxy,isx2);
michael@0: 
michael@0:               Count = 0;
michael@0:               isx = 0;
michael@0:               isy = 0;
michael@0:               isxy = 0;
michael@0:               isx2 = 0;
michael@0:            }
michael@0:            else
michael@0:            {
michael@0:               Count += 1;
michael@0:               isx += $1;
michael@0:               isy += $2;
michael@0:               isxy += $1 * $2;
michael@0:               isx2 += $1 * $1;
michael@0:            }
michael@0:         }
michael@0:      }
michael@0: 
michael@0: END {
michael@0:        if(Interval) {
michael@0:           print NR-Count, "-", NR, ":  ", regress(Count,isx,isy,isxy,isx2);
michael@0:        }
michael@0:        print regress(NR-Skip, sx, sy, sxy, sx2); 
michael@0:     }