program main

!*****************************************************************************80
!
!! chebyshev_interp_1d_test() tests chebyshev_interp_1d().
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    28 September 2012
!
!  Author:
!
!    John Burkardt
!
  implicit none

  integer prob
  integer prob_num

  call timestamp ( )
  write ( *, '(a)' ) ''
  write ( *, '(a)' ) 'CHEBYSHEV_INTERP_1D_TEST():'
  write ( *, '(a)' ) '  Fortran90 version'
  write ( *, '(a)' ) '  Test CHEBYSHEV_INTERP_1D().'
  write ( *, '(a)' ) '  The QR_SOLVE and R8LIB libraries are needed.'
  write ( *, '(a)' ) '  The test needs the TEST_INTERP library as well.'

  call p00_prob_num ( prob_num )
  do prob = 1, prob_num
    call test01 ( prob )
  end do
!
!  Terminate.
!
  write ( *, '(a)' ) ''
  write ( *, '(a)' ) 'CHEBYSHEV_INTERP_1D_TEST:'
  write ( *, '(a)' ) '  Normal end of execution.'
  write ( *, '(a)' ) ''
  call timestamp ( )

  stop 0
end
subroutine test01 ( prob )

!*****************************************************************************80
!
!! TEST01 tests CHEBYSHEV_VALUE_1D.
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    17 September 2012
!
!  Author:
!
!    John Burkardt
!
  implicit none

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

  real ( kind = rk ) int_error
  integer nd
  integer ni
  integer prob
  real ( kind = rk ) r8vec_norm_affine
  real ( kind = rk ), allocatable :: xd(:)
  real ( kind = rk ), allocatable :: xi(:)
  real ( kind = rk ), allocatable :: xy(:,:)
  real ( kind = rk ), allocatable :: yd(:)
  real ( kind = rk ), allocatable :: yi(:)

  write ( *, '(a)' ) ''
  write ( *, '(a)' ) 'CHEBYSHEV_INTERP_1D_TEST01:'
  write ( *, '(a,i6)' ) '  Interpolate data from TEST_INTERP problem #', prob

  call p00_data_num ( prob, nd )
  write ( *, '(a,i6)' ) '  Number of data points = ', nd

  allocate ( xy(1:2,1:nd) )

  call p00_data ( prob, 2, nd, xy )
  
  call r8mat_transpose_print ( 2, nd, xy, '  Data array:' )

  allocate ( xd(1:nd) )
  allocate ( yd(1:nd) )
  
  xd(1:nd) = xy(1,1:nd)
  yd(1:nd) = xy(2,1:nd)
!
!  #1:  Does interpolant match function at interpolation points?
!
  ni = nd

  allocate ( xi(1:ni) )
  allocate ( yi(1:ni) )

  xi(1:ni) = xd(1:nd)
  call chebyshev_interp_1d ( nd, xd, yd, ni, xi, yi )

  int_error = r8vec_norm_affine ( ni, yi, yd ) / real ( ni, kind = rk )

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

  deallocate ( xd )
  deallocate ( xi )
  deallocate ( xy )
  deallocate ( yd )
  deallocate ( yi )

  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