c----------------------------------------
      age0 = Age(0.60)
      age1 = Age(0.6020)
      age2 = Age(0.700)
         write(*,*) ' age=',age1-age0,age2-age0

         Stop
         end
c     -----------------------------
       Function Age(aexp)
c     -----------------------------
c                                  age for LCDM model 
       PARAMETER (Om0 =0.3)
       PARAMETER (tconst =9.31e+9)
       
       x = ((1.-Om0)/Om0)**0.333333*aexp
       Age = tconst /sqrt(1.-Om0)*(log(x**1.5+sqrt(1.+x**3)))

       Return
       End