DENSITY:boxes

input_variables

 If v is a vector, x and y are assumed to represent a  scattered set
 of points, where v is the altitude corresponding to the  location
 (x,y).

 If v is a matrix, x and y default to 1,2,3,....  If two vectors, x
 and y, are entered with the matrix v, the length of x must be greater
 than or equal to the number of columns of v and the length of y must
 be greater than or equal to the number of rows of v.

filled_boxes

 The boxes can be filled by setting the PHYSICA keyword  FILL  to the
 proper value, using the SET command.

        FILL   =  0  no filling  (the default)
  1 <= |FILL| <= 10  fill with hatch pattern |FILL|
 11 <= |FILL| <= 99  fill with dithering pattern nm, where n is the
                     increment number of dots to light up horizontally
                     and m is the increment number of dots to light up
                     vertically.
 If FILL < 0, then erase using |FILL| as above.

accentuate_a_range

 The optional parameters q1 and q2 can be used to accentuate a range
 of values.  If v_max is the maximum value of v and v_min is the
 minimum value of v, the full range of box sizes will be from:
 min = q1*(v_max-v_min)+v_min   to   max = q2*(v_max-v_min)+v_min
 The default values are: q1 = 0 and q2 = 1.

 The optional parameters p1 and p2 can be used to select a window of
 values from within this range, min to max, defined above. A box is
 drawn at (x,y) if and only if p1*(max-min)+min < v < p2*(max-min)+min.
 The default values are:  p1 = 0 and p2 = 1.