program main

!*****************************************************************************80
!
!! matrix_exponential_test() tests matrix_exponential().
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    26 November 2011
!
!  Author:
!
!    John Burkardt
!
  implicit none

  call timestamp ( )
  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) 'matrix_exponential_test():'
  write ( *, '(a)' ) '  Fortran90 version'
  write ( *, '(a)' ) '  Test matrix_exponential().'
  write ( *, '(a)' ) '  The C8LIB and R8LIB libraries are needed.'
  write ( *, '(a)' ) '  This test needs the TEST_MATRIX_EXPONENTIAL library.'

  call matrix_exponential_test01 ( )
  call matrix_exponential_test02 ( )
!
!  Terminate.
!
  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) 'MATRIX_EXPONENTIAL_TEST:'
  write ( *, '(a)' ) '  Normal end of execution.'
  write ( *, '(a)' ) ' '
  call timestamp ( )

  stop 0
end
subroutine matrix_exponential_test01 ( )

!*****************************************************************************80
!
!! MATRIX_EXPONENTIAL_TEST01 compares matrix exponential algorithms.
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    28 November 2011
!
!  Author:
!
!    John Burkardt
!
  implicit none

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

  real ( kind = rk ), allocatable :: a(:,:)
  real ( kind = rk ), allocatable :: a_exp(:,:)
  integer n
  integer test
  integer test_num

  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) 'MATRIX_EXPONENTIAL_TEST01:'
  write ( *, '(a)' ) '  R8MAT_EXPM1 is based on MATLAB''s matrix exponential function;'
  write ( *, '(a)' ) '  R8MAT_EXPM2 uses a Taylor series approach;'

  call r8mat_exp_test_num ( test_num )

  do test = 1, test_num

    write ( *, '(a)' ) ' '
    write ( *, '(a,i4)' ) '  Test #', test

    call r8mat_exp_story ( test )

    call r8mat_exp_n ( test, n )

    write ( *, '(a,i4)' ) '  Matrix order N = ', n

    allocate ( a(1:n,1:n) )

    call r8mat_exp_a ( test, n, a )

    call r8mat_print ( n, n, a, '  Matrix:' )

    allocate ( a_exp(1:n,1:n) )

    call r8mat_expm1 ( n, a, a_exp )
    call r8mat_print ( n, n, a_exp, '  EXPM1(A):' )

    call r8mat_expm2 ( n, a, a_exp )
    call r8mat_print ( n, n, a_exp, '  EXPM2(A):' )

    call r8mat_exp_expa ( test, n, a_exp )
    call r8mat_print ( n, n, a_exp, '  Exact Exponential:' )

    deallocate ( a )
    deallocate ( a_exp )

  end do

  return
end
subroutine matrix_exponential_test02 ( )

!*****************************************************************************80
!
!! MATRIX_EXPONENTIAL_TEST02 compares matrix exponential algorithms.
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    02 March 2013
!
!  Author:
!
!    John Burkardt
!
  implicit none

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

  complex ( kind = ck ), allocatable :: a(:,:)
  complex ( kind = ck ), allocatable :: a_exp(:,:)
  integer n
  integer test
  integer test_num

  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) 'MATRIX_EXPONENTIAL_TEST02:'
  write ( *, '(a)' ) '  C8MAT_EXPM1 is based on MATLAB''s matrix exponential function;'
  write ( *, '(a)' ) '  C8MAT_EXPM2 uses a Taylor series approach;'

  call c8mat_exp_test_num ( test_num )

  do test = 1, test_num

    write ( *, '(a)' ) ' '
    write ( *, '(a,i4)' ) '  Test #', test

    call c8mat_exp_story ( test )

    call c8mat_exp_n ( test, n )

    write ( *, '(a,i4)' ) '  Matrix order N = ', n

    allocate ( a(1:n,1:n) )

    call c8mat_exp_a ( test, n, a )

    call c8mat_print ( n, n, a, '  Matrix:' )

    allocate ( a_exp(1:n,1:n) )

    call c8mat_expm1 ( n, a, a_exp )
    call c8mat_print ( n, n, a_exp, '  EXPM1(A):' )

    call c8mat_exp_expa ( test, n, a_exp )
    call c8mat_print ( n, n, a_exp, '  Exact Exponential:' )

    deallocate ( a )
    deallocate ( a_exp )

  end do

  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