FUNCTION BETAH(R)
C     =================
C
C     Determination of the total pressure scale height
C     Solution of the transcendental equation by the Newton-Raphson method
C
      INCLUDE 'IMPLIC.FOR'
      PARAMETER (UN=1.D0,
     *           PISQ=1.77245385090551D0)
      IF(R.LT.0.88) THEN
         BET0=PISQ/2.D0/R
       ELSE
         BET0=UN+UN/3.D0/R/R
      END IF
C
      ITER=0
      BETA=BET0
   10 ITER=ITER+1
      B1=BETA-UN
      RB1=R*B1
      BSQ=SQRT(BETA*B1)
      ERF1=ERFCX(R*BSQ)
      ERF2=ERFCX(RB1)
      RHS=BSQ/B1*(UN-ERF1)+EXP(-R*RB1)*ERF2
      DP=R/PISQ*(2.D0-EXP(-R*BETA*RB1))+(UN-ERF1)/2.D0/B1/BSQ+
     *   R*R*EXP(-R*RB1)*ERF2
      DBETA=(RHS-2.D0/PISQ*BETA*R)/DP
      DEL=DBETA/BETA
      BETA=BETA+DBETA
      IF(ABS(DEL).GT.1.D-5.AND.ITER.LE.10) GO TO 10
      BETAH=BETA
      RETURN
      END