PLplot can draw graphs consisting of points with optional error bars,
line segments or histograms. Functions which perform each of these
actions may be called after setting up the plotting environment using
plenv
. All of the following functions draw within the box defined
by plenv
, and any lines crossing the boundary are clipped.
Functions are also provided for drawing surface and contour
representations of multi-dimensional functions. See Chapter 3, Advanced Use of PLplot for discussion of finer control of plot
generation.
plpoin
and plsym
mark out n
points
(x[i], y[i])
with the specified symbol. The
routines differ only in the interpretation of the symbol codes.
plpoin
uses an extended ASCII representation, with the printable
ASCII codes mapping to the respective characters in the current
font, and the codes from 0–31 mapping to various useful
symbols. In plsym
however, the code is a Hershey font code
number. Example programs are provided which display each of the
symbols available using these routines.
plpoin( | n, |
x, | |
y, | |
code) ; |
plsym
( | n, |
x, | |
y, | |
code) ; |
n
(PLINT
, input)
The number of points to plot.
x, y
(PLFLT *
, input)
Pointers to arrays of the coordinates of the
n
points.
code
(PLINT
,
input)
Code number of symbol to draw
PLplot provides two functions for drawing line graphs. All lines are drawn in the currently selected color, style and width. See the section called “Setting Line Attributes” for information about changing these parameters.
plline
draws a line or curve. The curve consists of
n-1
line segments joining the n
points in the input arrays. For single line segments, pljoin
is
used to join two points.
plline
( | n, |
x, | |
y) ; |
n
(PLINT
, input)
The number of points.
x, y
(PLFLT *
, input)
Pointers to arrays with coordinates of the n
points.
pljoin
( | x1, |
y1, | |
x2, | |
y2) ; |
x1, y1
(PLFLT
, input)
Coordinates of the first point.
x2, y2
(PLFLT
, input)
Coordinates of the second point.
plptex
allows text to be written within the limits set by plenv
.
The reference point of a text string may be located anywhere along an
imaginary horizontal line passing through the string at half the
height of a capital letter. The parameter
just
specifies where along this line the
reference point is located. The string is then rotated about the
reference point through an angle specified by the parameters
dx
and dy
, so that the
string becomes parallel to a line joining (x, y)
to (x+dx, y+dy)
.
plptex
( | x, |
y, | |
dx, | |
dy, | |
just, | |
text) ; |
x, y
(PLFLT
, input)
Coordinates of the reference point.
dx, dy
(PLFLT
, input)
These specify the angle at which the text is to be printed.
The text is written parallel to a line joining the points
(x, y)
to (x+dx, y+dy)
on the graph.
dx, dy
(PLFLT
, input)
These specify the angle at which the text is to be printed.
The text is written parallel to a line joining the points
(x, y)
to (x+dx, y+dy)
on
the graph.
just
(PLFLT
, input)
Determines justification of the string by specifying which
point within the string is placed at the reference point
(x, y)
. This parameter is a fraction of the
distance along the string. Thus if
, the
reference point is at the left-hand edge of the string. If
just
= 0.0
, it is at
the center and if just
= 0.5
, it is at the right-hand edge.
just
=
1.0
text
(char *
, input)
Pointer to the string of characters to be written.
Area fills are done in the currently selected color, line style, line width and pattern style.
plfill
fills a polygon. The polygon consists of
n
vertices which define the polygon.
plfill
( | n, |
x, | |
y) ; |
n
(PLINT
, input)
The number of vertices.
x, y
(PLFLT *
, input)
Pointers to arrays with coordinates of the n
vertices.
Functions plbin
and plhist
are provided for drawing histograms,
and functions plerrx
and plerry
draw error bars about specified
points. There are lots more too (see Chapter 18, The Common API for PLplot).