subroutine f(x,y,m)
        implicit none
        integer :: m
        real(8) :: x(m), y(m)

        y(2)= -((1d0/2d0)*x(1)*x(1)*x(1)-2d0*x(1)-x(2)+7d0)
        y(1)= -(exp(x(1))-x(2)+1d0)
    end subroutine