C	FUNCTION WHICH EVALUATES AN OPERAND AND RETURNS THE VALUE.
C	THE OPERAND IS (1) A NUMERIC CONSTANT OR (2) THE NAME OF
C	A VARIABLE WHOSE VALUE CAN BE DECODED TO A NUMERIC OR
C	(3) THE NAME OF A VARIABLE WHOSE VALUE IS THE NAME OF
C	ANOTHER VARIABLE ... WHOSE VALUE CAN BE DECODED.
C	(THIS ALLOWS THE USE OF PRE-DEFINED "VARIABLES" LIKE
C	"yes" AND "FALSE".
C
C  Submitted by:
C  
C  	R. N. Stillwell
C  	Institute for Lipid Research
C  	Baylor College of Medicine
C  	Houston, Texas 77030
C  	
C  (who would be glad to receive comments, suggestions, bug fixes, etc., but
C  who promises no support whatever).
C  
C  Literature reference:
C  
C  	R. N. Stillwell.  A low-overhead laboratory data management system
C  	for the PDP11.  Comput. Biomed. Res., 15, 29-38(1982).
C  
C  Acknowledgement:
C
C  	This software was developed under National Institutes of Health grants
C  	GM-13901 and GM-26611.
C 
C  General permission is hereby granted to copy, modify, or distribute this
C  program, but not for profit.  Copyright to this software is and shall
C  remain in the public domain.
C
C
	FUNCTION EVATOM(LATOM,ATBUF,EVALER)

	REAL EVATOM
	INTEGER LBUF,LATOM
	BYTE ATBUF(LATOM)
	LOGICAL*1 EVALER

	REAL*8 VARNAM
	BYTE VARBUF(40)
	EQUIVALENCE (VARNAM,VARBUF)

	BYTE VARVAL(40)
	DATA MAXVAR/40/
	INTEGER VARLEN
	INTEGER GETVAR

	EVALER = .FALSE.
	EVATOM = 0.0
C	COPY THE ARGUMENT INTO VARBUF
	VARNAM = '        '
	DO (I=1,LATOM) VARBUF(I) = ATBUF(I)
	LBUF = LATOM
	REPEAT UNTIL (VARLEN.LT.0)
	VARLEN = GETVAR(VARNAM,VARVAL,MAXVAR)
	IF (VARLEN.GE.0)
	VARNAM = '        '
	DO (I=1,VARLEN) VARBUF(I) = VARVAL(I)
	LBUF = VARLEN
	FIN
	FIN
C
C	CHOP TRAILING BLANKS AND TRY TO DECODE THE RESULT
C
	WHILE (LBUF.GT.0.AND.VARBUF(LBUF).EQ.' ') LBUF=LBUF-1
C
C	COMPLETELY BLANK FIELD RETURNS 0.0
C
	WHEN (LBUF.EQ.0) TEMP = 0.0
	ELSE DECODE (LBUF,1,VARBUF,ERR=9) TEMP
1	FORMAT (F40.0)
D	WRITE (5,9903) TEMP
D9903	FORMAT (' SUCCESSFUL DECODE: ',1PG15.6)
	EVATOM = TEMP		!SUCCESSFUL DECODE
	RETURN
	IF (.FALSE.)
9	EVALER = .TRUE.		!CONVERSION ERROR
D	WRITE (5,9905) LBUF,(VARBUF(I),I-1,LBUF)
D9905	FORMAT (' LBUF =',I6, 'VARBUF=',(1X,40A1))
	RETURN
	FIN
	END