#include <params.h>subroutine tricoef(n       ,a0nm    ,bpnm    ,bmnm    ,atri    , &                   btri    ,ctri    )!-----------------------------------------------------------------------!! Purpose:! Compute coefficients associated with solving the tri-diagonal system! of semi-implicit diverence equations in Normal Mode space.! NOTE 1:  Storage in the vectors assumed to be along columns ("N")! NOTE 2:  Eigenvalue part of "btri" not added here.  To be added later! in "TSTEP"!! Author:  J. Olson!!-----------------------------------------------------------------------!! $Id: tricoef.F90,v 1.2 2000/06/06 21:53:17 olson Exp $! $Author: olson $!!-----------------------------------------------------------------------  use precision  use pmgrid  implicit none!------------------------------Arguments--------------------------------!  integer , intent(in)   :: n         ! length of complex vector  real(r8), intent(in)   :: a0nm(2*n) ! wave # coefs (use in vert normal mode space)  real(r8), intent(in)   :: bpnm(2*n) ! wave # coefs (use in vert normal mode space)  real(r8), intent(in)   :: bmnm(2*n) ! wave # coefs (use in vert normal mode space)  real(r8), intent(out)  :: atri(2*n) ! wave # coefs (use in vert normal mode space)  real(r8), intent(out)  :: btri(2*n) ! wave # coefs (use in vert normal mode space)  real(r8), intent(out)  :: ctri(2*n) ! wave # coefs (use in vert normal mode space)!!---------------------------Local workspace-----------------------------!  integer  nn       ! n-wavenumber index  integer  nnm1     ! nn - 1  integer  nnp1     ! nn + 1  real(r8) tmp      ! real(r8) temp space  real(r8) tmpb1(2) ! real/imaginary temp spaces  real(r8) tmpb2(2) ! real/imaginary temp spaces  real(r8) denom    ! denominator!!-----------------------------------------------------------------------!! Perform "complex" arithmetic! NOTE:  Eigenvalue part of "btri" not added here.  To be added later! in "VERTNM"!  do nn = 1,n     nnm1 = nn - 1     nnp1 = nn + 1     atri(2*nn-1) = 0.     atri(2*nn  ) = 0.     ctri(2*nn-1) = 0.     ctri(2*nn  ) = 0.     tmpb1(1)     = 0.     tmpb1(2)     = 0.     tmpb2(1)     = 0.     tmpb2(2)     = 0.     if(nn .ne. 1) then        tmp          =  bmnm(2*nn  -1)*bpnm(2*nnm1-1)        denom        =  a0nm(2*nnm1-1)*a0nm(2*nnm1-1) + a0nm(2*nnm1  )*a0nm(2*nnm1  )        tmpb2(1)     =  a0nm(2*nnm1-1)*tmp/denom        tmpb2(2)     = -a0nm(2*nnm1  )*tmp/denom        tmp          =  bmnm(2*nn  -1)*bmnm(2*nnm1-1)        ctri(2*nn-1) = -a0nm(2*nnm1-1)*tmp/denom        ctri(2*nn  ) =  a0nm(2*nnm1  )*tmp/denom     endif     if(nn .ne. n) then        tmp          =  bpnm(2*nn  -1)*bmnm(2*nnp1-1)        denom        =  a0nm(2*nnp1-1)*a0nm(2*nnp1-1) + a0nm(2*nnp1  )*a0nm(2*nnp1  )        tmpb1(1)     =  a0nm(2*nnp1-1)*tmp/denom        tmpb1(2)     = -a0nm(2*nnp1  )*tmp/denom        tmp          =  bpnm(2*nn  -1)*bpnm(2*nnp1-1)        atri(2*nn-1) = -a0nm(2*nnp1-1)*tmp/denom        atri(2*nn  ) =  a0nm(2*nnp1  )*tmp/denom     endif!     btri(2*nn-1) = a0nm(2*nn-1) + tmpb1(1) + tmpb2(1)     btri(2*nn  ) = a0nm(2*nn  ) + tmpb1(2) + tmpb2(2)  end do!  returnend subroutine tricoef