gnuplot documentation
gnuplot documentation
gnuplot documentation
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
70 SET-SHOW <strong>gnuplot</strong> 4.3 127<br />
70.52 Polar<br />
The set polar command changes the meaning of the plot from rectangular coordinates to polar coordinates.<br />
Syntax:<br />
set polar<br />
unset polar<br />
show polar<br />
There have been changes made to polar mode in version 3.7, so that scripts for <strong>gnuplot</strong> versions 3.5 and<br />
earlier will require modification. The main change is that the dummy variable t is used for the angle so<br />
that the x and y ranges can be controlled independently. Other changes are: 1) tics are no longer put<br />
along the zero axes automatically — use set xtics axis nomirror; set ytics axis nomirror; 2) the<br />
grid, if selected, is not automatically polar — use set grid polar; 3) the grid is not labelled with angles<br />
— use set label as necessary.<br />
In polar coordinates, the dummy variable (t) is an angle. The default range of t is [0:2*pi], or, if degree<br />
units have been selected, to [0:360] (see set angles (p. 85)).<br />
The command unset polar changes the meaning of the plot back to the default rectangular coordinate<br />
system.<br />
The set polar command is not supported for splots. See the set mapping (p. 112) command for<br />
similar functionality for splot (p. 150)s.<br />
While in polar coordinates the meaning of an expression in t is really r = f(t), where t is an angle of<br />
rotation. The trange controls the domain (the angle) of the function, and the x and y ranges control<br />
the range of the graph in the x and y directions. Each of these ranges, as well as the rrange, may be<br />
autoscaled or set explicitly. See set xrange (p. 142) for details of all the ranges (p. 77) commands.<br />
Example:<br />
set polar<br />
plot t*sin(t)<br />
plot [-2*pi:2*pi] [-3:3] [-3:3] t*sin(t)<br />
The first plot uses the default polar angular domain of 0 to 2*pi. The radius and the size of the graph<br />
are scaled automatically. The second plot expands the domain, and restricts the size of the graph to<br />
[-3:3] in both directions.<br />
You may want to set size square to have <strong>gnuplot</strong> try to make the aspect ratio equal to unity, so that<br />
circles look circular. See also<br />
and<br />
polar demos (polar.dem)<br />
polar data plot (poldat.dem).<br />
70.53 Print<br />
The set print command redirects the output of the print command to a file.<br />
Syntax:<br />
set print<br />
set print "-"<br />
set print ""<br />
set print "" append<br />
set print "|"<br />
Without "", the output file is restored to . The "-" means<br />
. The append flag causes the file to be opened in append mode. A starting<br />
with "|" is opened as a pipe to the on platforms that support piping.
Change language