C     Calculate the period of pendulum as given in problem 14 on page
C     109 of Nyhoff and Leestma.  The angle of displacement and
C     pendulum length are entered by the user.
C
C     John Schneider
C     CptS 203, HW 2, problem 1
C-------------------------------------------------------------------------

      program pndulm
      implicit none
C.....
C     period = period of pendulum swings (s)
C     alpha  = angle of pendulum (entered in degrees)
C     length = length of pendulum (cm)
C     g      = acceleration due to gravity, 980.0 cm/s^2
C.....
      real period, alpha, length, g, pi
      parameter (g=980.0)

      pi = acos(-1.0)

      print *, 'Enter the length (in cm) of the pendulum.'
      read *, length

      print *,'Enter the angle (in degrees) of the pendulum.'
      read *, alpha
      alpha = alpha*pi/180.0

      period = 2.0*pi*sqrt(length/g)*(1.0 + sin(alpha/2)**2/4.0)

      print *, 'The period is ',period,' seconds.'

      stop
      end