SECTION 15.15 DENSITY PLOTS

This routine provides a density plot of an X and a Y variable.

The MAIN program should include

COMMON/BPRINT/IPT,NFILE,NDIG,NPUNCH,JPT,MFILE CALL DFLTThe call to the routine is

CALL DENSPLOT(X,N)

where

X is a REAL*4 array dimensioned X(N,2) and which contains in column 1 the X-variable and in column 2 the Y variable. N is the number of observations.

The range of X and Y values is divided into 60 equally spaced intervals and the number of observations with X and Y values falling in the various 3600 rectangles is counted. A plot is produced in which integers in a 60 by 60 grid represent the number of observations falling into each sub rectangle according to the following table:

Plotting symbol Digit Number of points 0 0 1 1 2 2 3 3 4 4-5 5 6-7 6 8-13 7 14-20 8 21-28 9 >28