C CALFF     SOURCE    CHAT      05/01/12    21:45:56     5004           
      SUBROUTINE CALFF(A,FE)
      IMPLICIT INTEGER(I-N)
      IMPLICIT REAL*8 (A-H,O-Z)
      IF((1+A).LT.1E-3) THEN
                      FE = -1.5
                 ELSE
         IF ((A-1).GT.-1E-3)  THEN
                      FE = -1.5 + DLOG(4.D0)
                 ELSE
                      B =  DSQRT(1.-A*A)
                      FE = -1.5 +((1+A)/2)*DLOG(2*(1+A))
     *                     + B* (DATAN((1+A)/B) - DATAN(A/B) )
         ENDIF
      ENDIF
      RETURN
      END