program cooling_simple
      write(*,*)'Initial Temperature?'
      read(*,*) T_ini
      write(*,*)'Surounding Temperature?'
      read(*,*) Ts
      write(*,*)'Cooling constant?'
      read(*,*) r
      dt = 0.01
      T = T_ini
      do i=1, 10000
        T = T - r*(T-Ts)*dt
        write(10) T
        if(mod(i,100)==0) write(*,*) T
      end do
      write(*,*) 'Detail temperature in file fort.10'
      end