program lorenzeuler

      real t,x,y,z,dt,tfinal
      real sigma,rho,beta
      integer n,steps

      dt = 0.0025
      tfinal = 40
      steps = tfinal/dt+1

      sigma = 10
      rho = 10
      beta = 8.0/3.0
      x = 1
      y = 1
      z = 1

      open(unit=13,file="data.d")

      do 10 n=1,steps
         write(13,*) t,x,y,z
         print *, t
         t = t + dt
         x = x + (sigma*(y - x))*dt
         y = y + (x*(rho - z)-y)*dt
         z = z + (x*y - beta*z)*dt

 10   continue

      end