sistu.f90

subroutine sistu(a, b)

!Resolución del sistema triangular superior
!Entrada:	a (matriz triangular superior)
!		b (términos independientes)
!Salida:	b (solución del sistema)

implicit none
real(8), intent (in) :: a(:,:)
real(8), intent (inout) :: b(:)
integer :: i, n

n = size(b)

do i= n, 1, -1
	b(i) = b(i)/a(i,i)
	b(1:i-1) = b(1:i-1)- a(1:i-1, i) * b(i)
end do

return
end subroutine