nnsc Subroutine

subroutine nnsc(N, R, C, Il, Jl, Ijl, L, D, Iu, Ju, Iju, U, Z, B, Tmp)

subroutine nnsc

numerical solution of sparse nonsymmetric system of linear

 equations given ldu-factorization (compressed pointer storage)


   input variables..  n, r, c, il, jl, ijl, l, d, iu, ju, iju, u, b
   output variables.. z

   parameters used internally..

 fia   - tmp   - temporary vector which gets result of solving  ly = b.
       -           size = n.

internal variables..

jmin, jmax - indices of the first and last positions in a row of
  u or l  to be used.

Arguments

Type IntentOptional Attributes Name
integer, intent(in) :: N
integer, intent(in), dimension(*) :: R
integer, intent(in), dimension(*) :: C
integer, intent(in), dimension(*) :: Il
integer, intent(in), dimension(*) :: Jl
integer, intent(in), dimension(*) :: Ijl
real(kind=dp), intent(in), dimension(*) :: L
real(kind=dp), intent(in), dimension(*) :: D
integer, intent(in), dimension(*) :: Iu
integer, intent(in), dimension(*) :: Ju
integer, intent(in), dimension(*) :: Iju
real(kind=dp), intent(in), dimension(*) :: U
real(kind=dp), intent(out), dimension(*) :: Z
real(kind=dp), intent(in), dimension(*) :: B
real(kind=dp), intent(inout), dimension(*) :: Tmp

Variables

Type Visibility Attributes Name Initial
integer, public :: i
integer, public :: j
integer, public :: jmax
integer, public :: jmin
integer, public :: k
integer, public :: ml
integer, public :: mu
real(kind=dp), public :: sum
real(kind=dp), public :: tmpk

Source Code

subroutine nnsc(N,R,C,Il,Jl,Ijl,L,D,Iu,Ju,Iju,U,Z,B,Tmp)
!
!      real l(*), d(*), u(*), b(*), z(*), tmp(*), tmpk, sum
integer , intent(in) :: N
integer , intent(in) , dimension(*) :: R
integer , intent(in) , dimension(*) :: C
integer , intent(in) , dimension(*) :: Il
integer , intent(in) , dimension(*) :: Jl
integer , intent(in) , dimension(*) :: Ijl
real(kind=dp) , intent(in) , dimension(*) :: L
real(kind=dp) , intent(in) , dimension(*) :: D
integer , intent(in) , dimension(*) :: Iu
integer , intent(in) , dimension(*) :: Ju
integer , intent(in) , dimension(*) :: Iju
real(kind=dp) , intent(in) , dimension(*) :: U
real(kind=dp) , intent(out) , dimension(*) :: Z
real(kind=dp) , intent(in) , dimension(*) :: B
real(kind=dp) , intent(inout) , dimension(*) :: Tmp
!
integer :: i , j , jmax , jmin , k , ml , mu
real(kind=dp) :: sum , tmpk
   !
   !   ******  set tmp to reordered b  *************************************
   do k = 1 , N
      Tmp(k) = B(R(k))
   enddo
   !   ******  solve  ly = b  by forward substitution  *********************
   do k = 1 , N
      jmin = Il(k)
      jmax = Il(k+1) - 1
      tmpk = -D(k)*Tmp(k)
      Tmp(k) = -tmpk
      if ( jmin<=jmax ) then
         ml = Ijl(k) - jmin
         do j = jmin , jmax
            Tmp(Jl(ml+j)) = Tmp(Jl(ml+j)) + tmpk*L(j)
         enddo
      endif
   enddo
   !   ******  solve  ux = y  by back substitution  ************************
   k = N
   do i = 1 , N
      sum = -Tmp(k)
      jmin = Iu(k)
      jmax = Iu(k+1) - 1
      if ( jmin<=jmax ) then
         mu = Iju(k) - jmin
         do j = jmin , jmax
            sum = sum + U(j)*Tmp(Ju(mu+j))
         enddo
      endif
      Tmp(k) = -sum
      Z(C(k)) = -sum
      k = k - 1
   enddo
end subroutine nnsc