DENSITY:solid_filled_regions
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).
A matrix is interpolated on these scattered points by means of a
Thiessen triangulation of the plane.
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 >= the
number of columns of v and the length of y must be >= the number of
rows of v.
To obtain solid filled histogram type regions in colour, use the
qualifier \HISTOGRAM. The range of values of the matrix is divided
into eight equal levels, and a different colour is associated with
each level. If the \HISTOGRAM qualifier is used, each matrix location
is represented by a rectangle of colour, centred on the matrix location.
The regions are not smoothly joined.
The optional scalars p1 and p2 can be used to broaden or shrink the
range of data values, from the full data range, min to max. If v is
a data value and if v < p1*(max-min)+min, that data value is treated
as min. If v > p2*(max-min)+min, that data value is treated as max.
The default values are: p1 = 0 and p2 = 1.
If the \LEGEND qualifier is used, a legend is drawn along the right
side of the axes. The legend requires the right end of the x-axis to
be set to 75% of the window, that is, %XUAXIS is set to 75. When a
profile is drawn, the axis borders must also be set to allow space
for the profiles, that is, %XUAXIS is set to 65% if a legend is
present, or 85% if there is no legend. By default, %XUAXIS is reset
to its former value. If the \NORESET qualifier is used, the axis
location is not reset after the density plot is done. The numeric
legend entries are written using the LEGFRMT format and with height
given by LEGSIZ, both of which are changed with the SET command.
If the \LOG qualifier is used, the range of values of the base 10
logarithm of the matrix is divided into equal levels, such that the
boundaries are integral powers of 10. If \LEGEND is also used,
the legend entries are written as powers of 10.