program cooling_simple_plot
      integer pgopen
      write(*,*)'Initial Temperature?'
      read(*,*) T_ini
      write(*,*)'Surounding Temperature?'
      read(*,*) Ts
      write(*,*)'Cooling constant?'
      read(*,*) r
      dt = 0.01
      T = T_ini
      if(pgopen('/xwin')<=0) stop
      call pgenv(0.0,100.0,0.0,100.0,0,1)
      call pglab('Time in minutes','Temperature in C','Colling Curve')
      do i=1, 10000
        T = T - r*(T-Ts)*dt
        write(10) T
c       if(mod(i,100)==0) write(*,*) T
        if(mod(i,100)==0) then
          if(T>=50.0) call pgsci(2)
          if(T<50.0) call pgsci(3)
          call pgpt(1,i*dt,T,20)
        endif
      end do
      write(*,*) 'Detail temperature in file fort.10'
      call pgclos
      end