SUBROUTINE TYPE54(TIME,XIN,OUT,T,DTDT,PAR,INFO,ICNTRL,*)
C***********************************************************************
C*    Copyright ASHRAE.  Toolkit for HVAC System Energy Calculations
C***********************************************************************
C*    SUBROUTINE:             MIXOSIM
C*
C*    LANGUAGE:               FORTRAN 77
C*
C*    PURPOSE:                To calculate the leaving temperature
C*                            and mass flow rate of two mixed streams
C*                            by simple conservation.
C***********************************************************************
C*    INPUT VARIABLES  DESCRIPTION(UNITS)                    SAMPLE VALUES
C*    XIN(1)  M1Ent  Mass flow rate of stream 1(kg/s)             2.0
C*    XIN(2)  T1Ent  Entering temperature of stream 1(C)          1.67
C*    XIN(3)  M2Ent  Mass flow rate of stream 2(kg/s)             1.65
C*    XIN(4)  T2Ent  Entering temperature of stream 2(C)         23.89
C*
C*    OUTPUT VARIABLES
C*    OUT(1)   MLvg  Mass flow rate of mixed stream(kg/s)         3.65
C*    OUT(2)   TLvg  Temperature of mixed stream(C)              11.7147
C*    OUT(3) ErrStat Error flag (0=ok, 1=error)(-)                0.0
C***********************************************************************
C     MAJOR RESTRICTION:      Specific heats equal for two streams.
C
C     DEVELOPER:              Shauna Gabel
C                             Michael J. Brandemuehl, PhD, PE
C                             University of Colorado at Boulder
C
C     DATE:                   January 1, 1992
C
C     INCLUDE FILES:          None
C     SUBROUTINES CALLED:     None
C     FUNCTIONS REQUIRED:     None
C
C     REVISION HISTORY:       None
C
C     REFERENCE:              None
C***********************************************************************
C*    INTERNAL VARIABLES
C*    small         Small number used in place of zero
C***********************************************************************

      INTEGER ErrStat, IOPT, NI, NP, ND
      DOUBLE PRECISION XIN, OUT
      DIMENSION XIN(4),OUT(3)
	CHARACTER*3 YCHECK(4), OCHECK(3)

      DATA small/1.E-9/
	DATA YCHECK/'MF2','TE1','MF2','TE1'/
	DATA OCHECK/'MF2','TE1','DM1'/

      M1ENT = XIN(1)
      T1ENT = XIN(2)
      M2ENT = XIN(3)
      T2ENT = XIN(4)
      
      ErrStat = 0
	IOPT	= -1
	NI		= 4		!CORRECT NUMBER OF INPUTS
	NP		= 0		!CORRECT NUMBER OF PARAMETERS
	ND		= 0		!CORRECT NUMBER OF DERIVATIVES

	IF (INFO(7).EQ.-1) THEN
		CALL TYPECK(IOPT,INFO,NI,NP,ND)
C	CHECKS TO SEE IF THE USER'S INFO MATCHES THE CORRECT NUMBER
		CALL RCHECK(INFO,YCHECK,OCHECK)
C	CHECKS TO SEE IN THE INPUT AND OUTPUT UNITS MATCH
	ENDIF

C1*** Calculate the mass flow rate of the mixed stream.

      MLvg = M1Ent+M2Ent

C1*** If leaving flow is zero, set leaving conditions to those of
C1    steam 1 and RETURN.

      IF (ABS(MLvg) .LE. small) THEN
        TLvg = T1Ent

      ELSE

C1*** Leaving flow is not zero.
C1*** Calculate the temperature of the mixed stream.

        TLvg = (M1Ent*T1Ent+M2Ent*T2Ent)/MLvg

      ENDIF

      OUT(1) = MLVG
      OUT(2) = TLVG
      OUT(3) = ERRSTAT

      RETURN 1
      END