@node Axis, Box, Aspect, Commands

@iftex
@syntax Axis.
@end iftex
@example
Syntax: AXIS A1 A2 VSMALL VBIG AX AY ALEN ILABEL ICLOCK
        AXIS A1 A2 VSMALL VBIG VLAB AX AY ALEN ILABEL ICLOCK
        AXIS A1 A2 ASMALL ABIG AX AY ALEN ILABEL ICLOCK
@end example
@pindex Axis
@findex axes, drawing

Makes an axis labeled from @code{A1} to @code{A2} at location @code{AX},
@code{AY}, length @code{ALEN}.
The first form (with @code{VSMALL} and @code{VBIG}) specifies the values
where you want small and big ticks explicitly; if you specify the string-valued
vector @code{VLAB} it will be used to label the big ticks.
The third form is more
obscure: If @code{ABIG} > 0 use that for spacing of large ticks.
If @code{ASMALL} < 0 make a logarithmic axis, if @code{ASMALL} = 0, do
the default. (See TICKSIZE for more on the meaning of negative
@code{ASMALL} and/or @code{ABIG}).
If @code{ASMALL} > 0 try to use that for the spacing of small ticks.

@code{ILABEL} is 0 for no labels, 1 for labels parallel to axis, 2 for
perpendicular to axis, and 3 for neither labels nor ticks.
@code{ANGLE} determines the angle of the axis.
If @code{ICLOCK} is even the ticks are anticlockwise on the axis,
if odd they are clockwise. You usually want the ticks perpendicular to
the axes, and this is what you get with @code{ICLOCK} 0 or 1; if it is
2 or 3 the ticks are vertical, and if 4 or 5 they are horizontal. The
labels are always on the opposite side of the axis from the ticks.

For example, if the limits were 0 1 0 1, then the following commands
would be equivalent to @code{BOX}:
@example
AXIS 0 1 0.05 0.2 3500 3500 27500 1 0
AXIS 0 1 0.05 0.2 3500 31000 27500 0 1
ANGLE 90
AXIS 0 1 0.05 0.2 3500 3500 27500 2 1
AXIS 0 1 0.05 0.2 31000 3500 27500 0 0
ANGLE 0
@end example
@noindent
(If expand is 1, that is).
If you want to label the bottom axis of some
plot only at prime points try
@example
SET b=@{1 2 3 5 7 11 13 17 19@} SET s=0,20
AXIS 0 20 s b 3500 3500 27500 1 0
@end example
@noindent
If you have used LIMITS to scale the axes and LOCATION or WINDOW
to move them, you could say something like
@example
AXIS $fx1 $fx2 s b $gx1 $gy1 $($gx2-$gx1) 1 0
@end example
An example of using your own string valued labels would be:
@example
set s=1,7,.5 set b=1,7 set labs=@{ O B A F G K M @}
LIMITS 1 7 0 0
AXIS 0 10 s b labs 3500 3500 27500 1 0
@end example
@noindent
which works as expected. If you don't have a shift key and try using
lower case (obafgkm) you'll be surprised as all the letters are not
at the same level (as they don't all have the same height). The easiest way
to deal with this is to make them all the same height:
@example
set labs=@{ o b a f g k m @} + '\\strut'
@end example
@noindent
(a strut is a @TeX{}ism that has the height and depth of a parenthesis;
I'm afraid that you do have to escape the \ in the string). If that leaves
too much space try:
@example
set labs='\\move 100' + @{ o b a f g k m @} + '\\strut'
@end example
@noindent
I think that you get the point.

Rather than use AXIS to draw all of your axes, it may be easier
to use BOX with some 3's to disable its axis-drawing habits. You'll
still get a box, but no ticks or labels. For example,
@example
LIMITS 0 1 0 10 BOX 1 2 0 3 TICKSIZE 0 0 -1 0 BOX 3 3 1 3
@end example
@noindent
will label the @i{y}-axis with both linear and logarithmic axes.

@emph{This was changed in V2.1: To specify logarithmic axes you should
now specify the logarithms, just as you do to BOX.} For example, to
draw a logarithmic axis running from 1 to 1000, 
specify @code{A1} as 0 and @code{A2} as 3, rather than 1 and 1000. 

See NOTATION if you want to control the use of floating point
or exponential notation.
If you want your positive and negative exponents to line up
define the SM variable @code{line_up_exponents}; if it's @code{1} they'll
be padded with a space, if @code{2} or more, with a @code{+}
(you can do this in your @file{.sm} file).