c=======================================================================
c     This routine defines the equations of motion for the driven 
c     triangle well.  It is used with twcmap.f
c=======================================================================
      subroutine fcn(t, y, f)

      implicit none

c-----------------------------------------------------------------------
c     common communication with main program
c-----------------------------------------------------------------------
      include 'fcn.inc'

c-----------------------------------------------------------------------
c     n: number of odes
c     t: time independent variable
c     y: solution (y(1)=x, y(2)=p)
c     f: derivative of solution
c-----------------------------------------------------------------------
      integer n
      parameter (n = 2)
      real t
      real y(n), f(n)

c-----------------------------------------------------------------------
c     evaluate derivatives
c-----------------------------------------------------------------------
      f(1) = y(2)/m
      f(2) = v0 + v*cos(w*t + theta)

      return

      end