SUBROUTINE SQRTBT(Z,ZRR) 15,1

      IMPLICIT NONE

      include 'champ.cdk'
      include 'chobs.cdk'

      COMPLEX  Z(IKTX,IKTY),sqBTZ(IKTX,IKTY)
      COMPLEX  sqBZZ(IKTX,IKTY)
      REAL     sigma,MZO, dist
      REAL     ZRR(N,N)
      INTEGER  jdata 
     
      EXTERNAL KR,RK,GAUSSIAN
      
      

      DO IW=1,IKTX
      DO JW = 1,IKTY
c        sqBTZ(IW,JW)=N*sqrt(2*Ftilde(IW,JW))*Z(IW,JW)
         sqBTZ(IW,JW)=sqrt(2*Ftilde(IW,JW))*Z(IW,JW)
         sqBTZ(IW,JW) = L(IW+KTX,JW)*sqBTZ(IW,JW)
      END DO
      END DO

      CALL KR(sqBTZ,ZRR,KTX,KTY,IKTX,IKTY,N,N2,LWRK,
     .                  FF1,FF2,FF3,WORK,TRIGS,IFAX,ZI)

      DO IW=1,N
      DO JW=1,N
         ZRR(IW,JW)=sigmab * ZRR(IW,JW)
      ENDDO
      ENDDO

      CONTINUE     
      END