program fly_drag_plot
      real m,k
      write(*,*)'Mass of your flying object?'
      read(*,*)m
      write(*,*)'Air friction Coefficent?'
      read(*,*)k

      write(*,*)'Please give me inital x'
      read(*,*)xini
      write(*,*)'and initial y'
      read(*,*)yini
      write(*,*)'initial Vx?'
      read(*,*)vx
      write(*,*)'initial Vy?'
      read(*,*)vy

      i_dummy=pgopen('/xwin')
      call pgenv(0.0,10.0,0.0,10.0,1,0)
      dt=0.000001

      x=xini
      y=yini
      
      do while(y>0)
        v=sqrt(vx**2+vy**2)
        fd=(-1)*k*v
        fdx=fd*vx/v
        fdy=fd*vy/v
       
        ax=fdx/m
        ay=-9.8+fdy/m
        vx=vx+ax*dt
        vy=vy+ay*dt
        x=x+vx*dt
        y=y+vy*dt
        call pgpt(1,x,y,-1)
      end do
      write(*,*)'Distance=',x,'Hight=',y
      call pgclos
      end