#*****************************************************************************80
#
## circle_scatters plots data in and out of a circle.
#
#  Licensing:
#
#    This code is distributed under the MIT license. 
#
#  Modified:
#
#    02 September 2020
#
#  Author:
#
#    John Burkardt
#
cat ( date ( ), "\n" )
cat ( "\n" )
cat ( "circle_scatters\n" )
cat ( " ", version$version.string, "\n" )
cat ( "  Make scatter plots of two sets of data representing" )
cat ( "  points inside, and points outside the unit circle." )
#
#  Read the data.
#
filename = "circle1_data.txt"
data1 <- read.table ( filename, header = FALSE )

filename = "circle2_data.txt"
data2 <- read.table ( filename, header = FALSE )
#
#  Generate points on a circle.
#
n = 50
circle = matrix ( nrow = n, ncol = 2 )
for ( i in 1 : n )
{
  theta = 2 * pi * ( i - 1 ) / ( n - 1 )
  circle[i,1] <- cos ( theta );
  circle[i,2] <- sin ( theta );
}
#
#  Plot the data
#
filename = "circle_scatters.png"

png ( filename )
plot ( circle[,1], circle[,2], 
  lwd = 3,
  type = "l",
  col = "black",
  xlab = "<--- X --->", 
  ylab = "<--- Y --->",
  main = "Random points inside/outside the unit circle" )
points ( data1[,1], data1[,2], col = "blue" )
points ( data2[,1], data2[,2], col = "red" )
grid ( )
cat ( '  Graphics saved as "', filename, '"\n' )
#
#  Terminate.
#
cat ( "\n" )
cat ( "circle_scatters:\n" )
cat ( "  Normal end of execution.\n" )

quit ( )