program main

!*****************************************************************************80
!
!! shepard_interp_2d_test() tests shepard_interp_2d().
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    21 September 2012
!
!  Author:
!
!    John Burkardt
!
  implicit none

  integer, parameter :: rk = kind ( 1.0D+00 )

  integer p_test_num
  parameter ( p_test_num = 4 )

  integer g
  integer j
  real ( kind = rk ) p
  real ( kind = rk ), dimension ( p_test_num ) :: p_test = (/ &
    1.0D+00, 2.0D+00, 4.0D+00, 8.0D+00 /)
  integer prob
  integer prob_num

  call timestamp ( )
  write ( *, '(a)' ) ''
  write ( *, '(a)' ) 'shepard_interp_2d_test():'
  write ( *, '(a)' ) '  FORTRAN90 version'
  write ( *, '(a)' ) '  Test SHEPARD_INTERP_2D().'
  write ( *, '(a)' ) '  The R8LIB library is needed.'
  write ( *, '(a)' ) '  This test also needs the TEST_INTERP_2D library.'

  call f00_num ( prob_num )
  g = 1

  do prob = 1, prob_num

    do j = 1, p_test_num
      p = p_test(j)
      call test01 ( prob, g, p )
    end do
  end do
!
!  Terminate.
!
  write ( *, '(a)' ) ''
  write ( *, '(a)' ) 'SHEPARD_INTERP_2D_TEST:'
  write ( *, '(a)' ) '  Normal end of execution.'
  write ( *, '(a)' ) ''
  call timestamp ( )

  stop 0
end
subroutine test01 ( prob, g, p )

!*****************************************************************************80
!
!! TEST01 tests SHEPARD_INTERP_2D.
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    21 September 2012
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, integer PROB, the problem number.
!
!    Input, integer G, the grid number.
!
!    Input, real ( kind = rk ) P, the power used in the distance weighting.
!
  implicit none

  integer, parameter :: rk = kind ( 1.0D+00 )

  logical, parameter :: debug = .false.
  integer g
  real ( kind = rk ) int_error
  integer nd
  integer ni
  real ( kind = rk ) p
  integer prob
  real ( kind = rk ) r8vec_norm_affine
  real ( kind = rk ), allocatable :: xd(:)
  real ( kind = rk ), allocatable :: xi(:)
  real ( kind = rk ), allocatable :: yd(:)
  real ( kind = rk ), allocatable :: yi(:)
  real ( kind = rk ), allocatable :: zd(:)
  real ( kind = rk ), allocatable :: zi(:)

  write ( *, '(a)' ) ''
  write ( *, '(a)' ) 'TEST01:'
  write ( *, '(a,i6)' ) '  Interpolate data from TEST_INTERP_2D problem #', prob
  write ( *, '(a,i6)' ) '  using grid #', g
  write ( *, '(a,g14.6)' ) '  using Shepard interpolation with P = ', p

  call g00_size ( g, nd )
  write ( *, '(a,i6)' ) '  Number of data points = ', nd

  allocate ( xd(1:nd) )
  allocate ( yd(1:nd) )
  call g00_xy ( g, nd, xd, yd )
  
  allocate ( zd(1:nd) )
  call f00_f0 ( prob, nd, xd, yd, zd )

  if ( debug ) then
    call r8vec3_print ( nd, xd, yd, zd, '  X, Y, Z data:' )
  end if
!
!  #1:  Does interpolant match function at interpolation points?
!
  ni = nd
  allocate ( xi(1:ni) )
  allocate ( yi(1:ni) )
  xi(1:ni) = xd(1:ni)
  yi(1:ni) = yd(1:ni)

  allocate ( zi(1:ni) )
  call shepard_interp_2d ( nd, xd, yd, zd, p, ni, xi, yi, zi )

  int_error = r8vec_norm_affine ( nd, zi, zd ) / real ( ni, kind = rk )

  write ( *, '(a)' ) ''
  write ( *, '(a,g14.6)' ) &
    '  L2 interpolation error averaged per interpolant node = ', &
    int_error

  deallocate ( xd )
  deallocate ( xi )
  deallocate ( yd )
  deallocate ( yi )
  deallocate ( zd )
  deallocate ( zi )

  return
end
subroutine timestamp ( )

!*****************************************************************************80
!
!! timestamp() prints the current YMDHMS date as a time stamp.
!
!  Example:
!
!    31 May 2001   9:45:54.872 AM
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    15 August 2021
!
!  Author:
!
!    John Burkardt
!
  implicit none

  character ( len = 8 ) ampm
  integer d
  integer h
  integer m
  integer mm
  character ( len = 9 ), parameter, dimension(12) :: month = (/ &
    'January  ', 'February ', 'March    ', 'April    ', &
    'May      ', 'June     ', 'July     ', 'August   ', &
    'September', 'October  ', 'November ', 'December ' /)
  integer n
  integer s
  integer values(8)
  integer y

  call date_and_time ( values = values )

  y = values(1)
  m = values(2)
  d = values(3)
  h = values(5)
  n = values(6)
  s = values(7)
  mm = values(8)

  if ( h < 12 ) then
    ampm = 'AM'
  else if ( h == 12 ) then
    if ( n == 0 .and. s == 0 ) then
      ampm = 'Noon'
    else
      ampm = 'PM'
    end if
  else
    h = h - 12
    if ( h < 12 ) then
      ampm = 'PM'
    else if ( h == 12 ) then
      if ( n == 0 .and. s == 0 ) then
        ampm = 'Midnight'
      else
        ampm = 'AM'
      end if
    end if
  end if

  write ( *, '(i2.2,1x,a,1x,i4,2x,i2,a1,i2.2,a1,i2.2,a1,i3.3,1x,a)' ) &
    d, trim ( month(m) ), y, h, ':', n, ':', s, '.', mm, trim ( ampm )

  return
end