subroutine jacob_f(x,A,m)
        implicit none
        integer :: m
        real(8) :: x(m), a(m,m)
        A(1,1) = exp(x(1))
        A(1,2) = -1d0
        A(2,1) = ((3d0/2d0)*x(1)*x(1))-2d0
        A(2,2) = -1d0
    end subroutine