`Write a routine that solves a system after knowing its LU decomposition.
Input arguments:
`

- , a compact decomposition, as computed by the routine at point 1.
- , teh integer vector of permutations, as computed by the routine at point 1.
- , a right hand vector.

`Output arguments:
`

- , containing the solution of the system; the input value of is overwritten.

`The header and the declarations of this routine should be
`

subroutine FB_Subst(A,b,Pivot) implicit none ! The LU factorization, as given by LU_Fact real, intent(in), dimension(:,:) :: A ! The RHS vector real, intent(inout), dimension(:) :: b ! Vector of permutations, as given by LU_Fact integer, dimension(:), intent(in) :: Pivot .....................................

`The routines LU_Fact and FB_Subst will both be
submitted in the same file, lin_solve.f90.
`

Adrian Sandu 2001-08-26