C     auxiliary routine for sphfpt
      SUBROUTINE derivs(x,y,dydx)
      INTEGER m,n
      REAL c2,dx,gamma,x,dydx(3),y(3)
      COMMON /sphcom/ c2,gamma,dx,m,n
      dydx(1)=y(2)
      dydx(2)=(2.0*x*(m+1.0)*y(2)-(y(3)-c2*x*x)*y(1))/(1.0-x*x)
      dydx(3)=0.0
      return
      END