program main

c*********************************************************************72
c
cc ball_grid_test tests ball_grid().
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    10 November 2011
c
c  Author:
c
c    John Burkardt
c
      implicit none

      call timestamp ( )
      write ( *, '(a)' ) ' '
      write ( *, '(a)' ) 'ball_grid_test():'
      write ( *, '(a)' ) '  FORTRAN77 version'
      write ( *, '(a)' ) '  Test ball_grid().'

      call ball_grid_test01 ( )
c
c  Terminate.
c
      write ( *, '(a)' ) ' '
      write ( *, '(a)' ) 'ball_grid_test():'
      write ( *, '(a)' ) '  Normal end of execution.'
      write ( *, '(a)' ) ' '
      call timestamp ( )

      return
      end
      subroutine ball_grid_test01 ( )

c*********************************************************************72
c
cc BALL_GRID_TEST01 tests BALL_GRID.
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    10 November 2011
c
c  Author:
c
c    John Burkardt
c
      implicit none

      double precision bg(3,5000)
      double precision c(3)
      character * ( 80 ) filename
      integer n
      integer ng
      double precision r

      write ( *, '(a)' ) ' '
      write ( *, '(a)' ) 'TEST01:'
      write ( *, '(a)' ) '  BALL_GRID can define a grid of points'
      write ( *, '(a)' ) 
     &  '  with N+1 points on a horizontal or vertical radius,'
      write ( *, '(a)' ) '  based on any ball.'

      n = 10
      r = 2.0D+00
      c(1) = 1.0D+00
      c(2) = 5.0D+00
      c(3) = 2.0D+00

      write ( *, '(a)' ) ' '
      write ( *, '(a,i8)' ) '  We use N = ', n
      write ( *, '(a,g14.6)' ) '  Radius R = ', r
      write ( *, '(a,g14.6,a,g14.6,a,g14.6,a)' ) 
     &  '  Center C = (', c(1), ',', c(2), ',', c(3), ')'

      call ball_grid_count ( n, r, c, ng )

      write ( *, '(a)' ) ' '
      write ( *, '(a,i8)' ) '  Number of grid points will be ', ng

      call ball_grid ( n, r, c, ng, bg )

      call r83vec_print_part ( ng, bg, 20, 
     &  '  Part of the grid point array:' )

      filename = 'ball_grid_test01.xyz'

      call r8mat_write ( filename, 3, ng, bg )

      write ( *, '(a)' ) ' '
      write ( *, '(a)' ) 
     &  '  Data written to the file "' // trim ( filename ) // '".'

      return
      end