FUNCTION ERFCIN(X)
C     ==================
C
C     Approximate inverse complementary error function inverfc(x)
C
      INCLUDE 'IMPLIC.FOR'
      parameter (pisq=1.77245385090551D0, pisq2=pisq/2.d0)
      XL=-LOG(X)
      REL=0.88623D0+XL*(7.4871471D-3-XL*1.7726701D-4)
      E=SQRT(-LOG(X*(2.D0-X)))*REL
      iterr=0
   10 continue
      iterr=iterr+1
      dele=(erfcx(e)-x)*pisq2*exp(e*e)
      err=abs(dele/e)
      e=e+dele
      if(err.gt.1.e-6.and.iterr.lt.10) go to 10
      erfcin=e
      RETURN
      END