Axes

The axes commands include:

Axis, Grid, and Grid Cross.

Axis

This command is used to draw and label a set of axes around the viewport. The label increment in user units (e.g. longitude, latitude), tic increments, and placement options are specified. The axes are drawn on the current output device.

The box that is drawn around the viewport as part of the axes, corresponds to the user window extrema, and the viewport boundary. The labels are plotted inside or outside the viewport boundary. The label size depends on the current Character_Height() and line stroke characteristics depend on the current Line_Type() and Line_Width().

The parameters are:

a - x axis label increment (+ive value, 0 » no x labels),

b - y axis label increment (+ive value, 0 » no y labels),

c - x axis tic increment (+ive value, 0 » no tics),

d - y axis tic increment (+ive value, 0 » no tics),

e - left axis flag (1 » use the supplied increment values; 0 » no labels or tics; -1 » no labels, tics or line),

f - right axis flag (1 » use the supplied increment values; 0 » no labels or tics; -1 » no labels, tics or line),

g - bottom axis flag (1 » use the supplied increment values; 0 » no labels or tics; -1 » no labels, tics or line),

h - top axis flag (1 » use the supplied increment values; 0 » no labels or tics; -1 » no labels, tics or line),

i - tics and labels on the inside/outside flag (0»outside, 1»inside).

Axis(a,b,c,d,e,f,g,h,i);

/* labels @ 1 unit, tics @ 0.1 unit on the left & bottom edges */
Axis(1,1,0.1,0.1,1,0,1,0,0);

See the example Data Points and Labels

Grid

This command is used to draw a grid of grid lines over the user window. The grid line increments in user units (e.g. longitude, latitude) are specified. The lines will occur at the increment intervals in user units (e.g. if the increment is 1, the grid lines will be drawn at each integer value along the axis with an increment of 1 between each grid line, independently of the values of at the edges of the plot window). If the optional grid offset values are supplied the grid lines will be offset from the "e;natural"e; increment positions by the offset amount (in user units).

The line stroke characteristics depend on the current Line_Type() and Line_Width().

There are 2 or more parameters:

x increment- x axis grid increment in user units.

y increment- y axis grid increment in user units.

x offset - x axis grid offset in user units.

y offset - y axis grid offset in user units.

Grid(x increment,y increment[,x offset, y offset]);

Grid(1,1);

Grid Cross

This command is used to draw a set of grid intersection crosses over the user window. The grid cross increment between adjacent crosses in user units (e.g. longitude, latitude) and the size of the cross strokes (mm) are specified. The crosses will occur evenly at the increment intervals in user units.

There are 3 parameters:

x increment- x axis grid increment in user units.

y increment- y axis grid increment in user units. cross size - grid cross size in mm.

Grid_Cross(x increment,y increment,cross size);

Grid_Cross(0.5,0.5,2); /* 2 mm crosses at every 0.5 unit */