tsp_display <- function ( prefix, n, x )

#*****************************************************************************80
#
## tsp_display() plots cities and a tour connecting them.
#
#  Discussion:
#
#    The code now automatically closes the loop by returning to the first city.
#
#  Licensing:
#
#    This code is distributed under the MIT license. 
#
#  Modified:
#
#    27 July 2026
#
#  Author:
#
#    John Burkardt
#
#  Input:
#
#    string prefix: a string that defines the name of the problem.  
#
#    integer n: the number of cities.
#
#    real x(n,2): the x and y coordinates of the cities.
#
{
  filename = paste0 ( prefix, ".png" )

  png ( filename )

  plot ( c ( x[,1], x[1,1] ), c ( x[,2], x[1,2] ),
    xlab = "<--- X --->",
    ylab = "<--- Y --->",
    main = prefix,
    col = "blue",
    type = 'l' )

  grid ( nx = 5, ny = 5, col = "black" )

  cat ( '  Graphics saved as "', filename, '"\n' )

  return ( )
}