Assumption:
Circle CIR measured with an even number of points, spread all around.
Method:
Compute all diameters, find the shortest and longest. This is done by simple coordinate distance [SQRT((X1-X0)^2 + (Y1-Y0)^2) ], but the twist is that PC-DMIS can do it for all diameters at once! It just takes three lines.
ASSIGN/V1=(CIR.HIT[1..CIR.NUMHITS/2].X-CIR.HIT[CIR.NUMHITS/2+1..CIR.NUMHITS].X)^2 ; square the X-diffs
ASSIGN/V2=(CIR.HIT[1..CIR.NUMHITS/2].Y-CIR.HIT[CIR.NUMHITS/2+1..CIR.NUMHITS].Y)^2 ; square the Y-diffs
ASSIGN/V3=SQRT(V1+V2) ; add them and extract square roots
ASSIGN/MX=MAX(V3)
ASSIGN/MXI=MAXINDEX(V3)
ASSIGN/MN=MIN(V3)
ASSIGN/MNI=MININDEX(V3)
COMMENT/REPT,
"Maxindex: "+MXI
"Max : "+MX
"Minindex: "+MNI
"Min : "+MN
