#*****************************************************************************80
#
## lissajous_plot draws a closed planar curve.
#
#  Licensing:
#
#    This code is distributed under the MIT license.
#
#  Modified:
#
#    18 August 2020
#
#  Author:
#
#    John Burkardt
#
cat ( "\n" )
cat ( "lissajous_plot:\n" )
cat ( " ", version$version.string, "\n" )
cat ( "  Make a plane curve by connecting a series of points.\n" )
cat ( "  Also mark every 10th point.\n" )

filename = "lissajous_data.txt"
xy <- read.table ( filename, header = FALSE )

filename = "lissajous_plot.png"
png ( filename )

n = dim ( xy )[1]
sample = seq ( 1, n, by = 10 )

plot ( xy[sample,1], xy[sample,2],
  xlab = "<--- X --->",
  ylab = "<--- Y --->",
  main = "Lissajous, x=sin(3t+pi/2), y=sin(4t)" )
lines ( xy[,1], xy[,2], type = 'l', col = "magenta" )
grid ( )
cat ( "\n" )
cat ( '  Graphics saved as "', filename, '"\n' )
#
#  Terminate.
#
cat ( "\n" )
cat ( "lissajous_plot\n" )
cat ( "  Normal end of execution.\n" )
quit ( )