SUBROUTINE SETDRT
C     =================
C
      INCLUDE 'IMPLIC.FOR'
      INCLUDE 'BASICS.FOR'
      INCLUDE 'MODELQ.FOR'
      COMMON/RHODER/DRHODT(MDEPTH)
      PARAMETER(DDTMIN=0., DDTPLU=0.001)
C
      DO ID=1,ND
         T=TEMP(ID)
         P=PTOTAL(ID)
         RHO1=RHOEOS(T*(UN-DDTMIN),P)
         RHO2=RHOEOS(T*(UN+DDTPLU),P)
         DRHODT(ID)=(RHO2-RHO1)/T/(DDTMIN+DDTPLU)
      END DO
      RETURN
      END