*$ CREATE RFRNDX.FOR
*COPY RFRNDX
*
*=== Rfrndx ===========================================================*
*
      DOUBLE PRECISION FUNCTION RFRNDX ( WVLNGT, OMGPHO, MMAT )

      INCLUDE '(DBLPRC)'
      INCLUDE '(DIMPAR)'
      INCLUDE '(IOUNIT)'
*
*----------------------------------------------------------------------*
*                                                                      *
*     Copyright (C) 1998-2005      by    Alfredo Ferrari & Paola Sala  *
*     All Rights Reserved.                                             *
*                                                                      *
*                                                                      *
*     user defined ReFRaction iNDeX:                                   *
*                                                                      *
*     Created on 19 september 1998 by    Alfredo Ferrari & Paola Sala  *
*                                                   Infn - Milan       *
*                                                                      *
*     Last change on 25-oct-02     by    Alfredo Ferrari               *
*                                                                      *
*                                                                      *
*----------------------------------------------------------------------*
*     
      IF (MMAT.EQ.26)THEN
         RFRNDX=1.58
      elseIF (MMAT.EQ.27)THEN
         WW=WVLNGT
         RFRNDX=(0.5271D0*WW**3.+0.4576D0*WW**2+1.273D0*WW-1.683D-5)
     &        /(WW**4.+0.9436D0*WW**3.+0.6375D0*WW**2.+0.9658D0*WW
     &        -1.326D-5)
      ENDIF
      RETURN
*===  End of function Rfrndx ===========================================*
      END

