The following script demonstrates how you can use the
FILTER
command to smooth data. See Figure 1.
X=[0:4:.05]
Y=X^2-3*X+3+SIN(X*3)*RAN(X)*2
WINDOW 5
GRAPH\AXESONLY X Y
GET XMIN XMIN
GET XMAX XMAX
GET YMIN YMIN
GET YMAX YMAX
SCALES XMIN XMAX YMIN YMAX
SET PLOTSYMBOL -1
GRAPH\OVERLAY X Y
SET PLOTSYMBOL 0
WINDOW 6
FILTER\-RECURSIVE Y YF [-36;9;44;69;84;89;84;69;44;9;-36]
SCALES XMIN XMAX YMIN YMAX
GRAPH X YF/429
WINDOW 7
FILTER\-RECURSIVE Y YF [18;-45;-10;60;120;143;120;60;-10;-45;18]
SCALES XMIN XMAX YMIN YMAX
GRAPH X YF/429
WINDOW 8
FILTER\-RECURSIVE Y YF [-3;-6;-5;3;21;46;67;74;67;46;21;3;-5;-6;-3]
SCALES XMIN XMAX YMIN YMAX
GRAPH X YF/320
FILTER
example showing data smoothing
The following script demonstrates how you can use the
FILTER
command to differentiate data. See Figure 2.
X=[0:4:.2]
H=X[2]-X[1]
Y=X^2-3*X+3
WINDOW 5
SET PLOTSYMBOL -1
GRAPH X Y
WINDOW 7
SET PLOTSYMBOL 0
FILTER\-RECURSIVE Y YF [-4;30;-120;40;60;-6]
SCALES 0 4 -3 5
SET PLOTSYMBOL -2
GRAPH X YF/(120*H)
SET PLOTSYMBOL 0
GRAPH\OVERLAY X 2*X-3
FILTER
example showing the first derivative