.TH HENWARP 1
.SH NAME
.PD 0
.TP
henwarp \- warps a square into the phase space of the Henon system
.PD 1
.SH SYNOPSIS
.PD 0
.TP
.B henwarp \fB-help
.LP
\ \ or
.TP
.B henwarp
\fB[\-width \fIinteger\fP]
[\-height \fIinteger\fP]
[\-swap]
[\-len \fIinteger\fP]
[\-count \fIinteger\fP]
[\-A \fIdouble\fP]
[\-B \fIdouble\fP]
[\-ulx \fIdouble\fP]
[\-uly \fIdouble\fP]
[\-lly \fIdouble\fP]
[\-inv]
[\-mag \fIinteger\fP]
[\-term \fIstring\fP]
.PD 1
.SH DESCRIPTION
A square (initially centered about the origin) is transformed by the Henon
system, which is described by the equation x(t+1) = A - x(t)^2 + B *
x(t - 1), a fixed number of times according to the specified parameters.
.SH OPTIONS
.IP \fB\-width\ \fIinteger\fP
Width of the plot in pixels.
.IP \fB\-height\ \fIinteger\fP
Height of the plot in pixels.
.IP \fB\-swap
Swap the x and y axis.
.IP \fB\-len\ \fIinteger\fP
Length of edge of square.
.IP \fB\-count\ \fIinteger\fP
Number of transformations.
.IP \fB\-A\ \fIdouble\fP
Value of the A parameter.
.IP \fB\-B\ \fIdouble\fP
Value of the B parameter.
.IP \fB\-ulx\ \fIdouble\fP
Upper-left corner x-coordinate.
.IP \fB\-uly\ \fIdouble\fP
Upper-left corner y-coordinate.
.IP \fB\-lly\ \fIdouble\fP
Lower-left corner y-coordinate.
.IP \fB\-inv
Invert all colors?
.IP \fB\-mag\ \fIinteger\fP
Magnification factor.
.IP \fB\-term\ \fIstring\fP
How to plot points.
.SH MISCELLANY
You may wish to try this with a small length for the size of
square and watch how the resulting plot changes as you slowly
increase the value passed to the -count option starting at
zero. The square will slowly spread out and converge to the
attractor of the system.
The method for choosing the viewable region may seem
counter-intuitive at first, but it has some nice properties. In
particular, selecting the exact (x, y) coordinates for the
upper-left corner and only selecting the lower right y coordinate
forces both the x and y scales to be identical since all scales
are uniquely determined by these values along with the plot
width and height. If you then change the width or height of the
plot, the relative scales will still match up. The options for
making a box work similarly.
.SH BUGS
The length of the square is in pixels and works best if it is
an odd value. With even numbered values it can produce a gap
in the plot for small values supplied with the -count option.
No sanity checks are performed to make sure that any of the
options make sense.
.SH AUTHOR
Copyright (c) 1997, Gary William Flake.
Permission granted for any use according to the standard GNU
``copyleft'' agreement provided that the author's comments are
neither modified nor removed. No warranty is given or implied.