Program FactorHW
c     This program uses the power series for e^x to compute variables
c     of a pre-defined set to find cosh(x) and compares them to those of
c     power series.
c     ****Nathan Hayes 4/16/08****

      real ans, ans2, x
      print *, '   X       Power Series     CosH(X)'
      print *, '===================================='

      do 30 x = -1.0, 1.1 , 0.1
        ans = (fexp(x) + (1./fexp(x)))/2.
        ans2 = cosh(x)
        print 20, x, ans, ans2
20    format(1x, f5.1, 2f15.5)
30    continue
      end

c     ****Function to caluculate the series****

      real function fexp(e)
      integer k
      external Factor
      real e, subexp
      k = 0
      fexp = 0
      subexp = 1
      do while (abs(subexp) .gt. 1e5)
         fexp = fexp+subexp
         k = k + 1
         subexp = e**k/factor(k)
         enddo
      return
      end
      
c     ****Function to caluclate the factorial***

      function Factor(f)
      integer  i, f
      Factor = 1
      do 10 i=1,f
         factor=factor*i
10    continue
      return
      end