double precision zz,y,yc,diff,h,w
      integer npoint,np,npel
      common /deriv/ zz(8,maxpoint),y(4,maxpoint),
     &  yc(4,maxpoint),diff(4,maxpoint),h(maxvar,maxvar),
     &  w(4,maxpoint),npoint,np(-2:2,-2:2),npel(-2:2,-2:2)