code: def _vminFindStart(v,E,Lz,I3V,delta,u0,cosh2u0,sinh2u0,
                                  potu0pi2,pot):
      
      vtry= 0.9*v
      while _JzStaeckelIntegrandSquared(vtry,
                                        E,Lz,I3V,delta,u0,cosh2u0,sinh2u0,
                                        potu0pi2,pot) >= 0. \
                                        and vtry > 0.000000001:
          vtry*= 0.9
      if vtry < 0.000000001: return 0.   
      return vtry
docs: NAME:
         _vminFindStart
      PURPOSE:
         Find adequate start point to solve for vmin
      INPUT:
         same as JzStaeckelIntegrandSquared
      OUTPUT:
         rstart
      HISTORY:
         2012-11-28 - Written - Bovy (IAS)