*DECK ZErMsg
      SUBROUTINE ZErMsg (LIBRAR, SUBROU, MESSG, NERR, LEVEL)
C***BEGIN PROLOGUE  ZErMsg
C***PURPOSE  Process error messages for SLATEC and other libraries.
C***LIBRARY   SLATEC (XERROR)
C***CATEGORY  R3C
C***TYPE      ALL (ZErMsg-A)
C***KEYWORDS  ERROR MESSAGE, XERROR
C***AUTHOR  (XERMSG) Fong, Kirby, (NMFECC at LLNL)
C***AUTHOR2 (ZErMsg) Bob Walker -- mods to use own ZError routine
C***DESCRIPTION
C
C   ZErMsg processes a diagnostic message in a manner determined by the
C   value of LEVEL and the current value of the library error control
C   flag, KONTRL.  See subroutine XSETF for details.
C
C    LIBRAR   A character constant (or character variable) with the name
C             of the library.  This will be 'SLATEC' for the SLATEC
C             Common Math Library.  The error handling package is
C             general enough to be used by many libraries
C             simultaneously, so it is desirable for the routine that
C             detects and reports an error to identify the library name
C             as well as the routine name.
C
C    SUBROU   A character constant (or character variable) with the name
C             of the routine that detected the error.  Usually it is the
C             name of the routine that is calling ZErMsg.  There are
C             some instances where a user callable library routine calls
C             lower level subsidiary routines where the error is
C             detected.  In such cases it may be more informative to
C             supply the name of the routine the user called rather than
C             the name of the subsidiary routine that detected the
C             error.
C
C    MESSG    A character constant (or character variable) with the text
C             of the error or warning message.  In the example below,
C             the message is a character constant that contains a
C             generic message.
C
C                   CALL ZErMsg ('SLATEC', 'MMPY',
C                  *'THE ORDER OF THE MATRIX EXCEEDS THE ROW DIMENSION',
C                  *3, 1)
C
C    NERR     An integer value that is chosen by the library routine's
C             author.  It must be in the range -99 to 999 (three
C             printable digits).  Each distinct error should have its
C             own error number.  These error numbers should be described
C             in the machine readable documentation for the routine.
C             The error numbers need be unique only within each routine,
C             so it is reasonable for each routine to start enumerating
C             errors from 1 and proceeding to the next integer.
C
C    LEVEL    An integer value in the range 0 to 2 that indicates the
C             level (severity) of the error.  Their meanings are
C
C            -1  A warning message.  This is used if it is not clear
C                that there really is an error, but the user's attention
C                may be needed.  An attempt is made to only print this
C                message once.
C
C             0  A warning message.  This is used if it is not clear
C                that there really is an error, but the user's attention
C                may be needed.
C
C             1  A recoverable error.  This is used even if the error is
C                so serious that the routine cannot return any useful
C                answer.  If the user has told the error package to
C                return after recoverable errors, then ZErMsg will
C                return to the Library routine which can then return to
C                the user's routine.  The user may also permit the error
C                package to terminate the program upon encountering a
C                recoverable error.
C
C             2  A fatal error.  ZErMsg will not return to its caller
C                after it receives a fatal error.  This level should
C                hardly ever be used; it is much better to allow the
C                user a chance to recover.  An example of one of the few
C                cases in which it is permissible to declare a level 2
C                error is a reverse communication Library routine that
C                is likely to be called repeatedly until it integrates
C                across some interval.  If there is a serious error in
C                the input such that another step cannot be taken and
C                the Library routine is called again without the input
C                error having been corrected by the caller, the Library
C                routine will probably be called forever with improper
C                input.  In this case, it is reasonable to declare the
C                error to be fatal.
C
C***REFERENCES  R. E. Jones and D. K. Kahaner, XERROR, the SLATEC
C                 Error-handling Package, SAND82-0800, Sandia
C                 Laboratories, 1982.
C***END PROLOGUE  ZErMsg
      CHARACTER*(*) LIBRAR, SUBROU, MESSG
      CHARACTER*8 XLIBR, XSUBR
      CHARACTER*72  TEMP
      character*80  Line
      CHARACTER*20  LFIRST
C***FIRST EXECUTABLE STATEMENT  ZErMsg
C
C       WE PRINT A FATAL ERROR MESSAGE AND TERMINATE FOR AN ERROR IN
C          CALLING ZErMsg.  THE ERROR NUMBER SHOULD BE POSITIVE,
C          AND THE LEVEL SHOULD BE BETWEEN 0 AND 2.
C
      IF (NERR.LT.-9999999 .OR. NERR.GT.99999999 .OR. NERR.EQ.0 .OR.
     *   LEVEL.LT.-1 .OR. LEVEL.GT.2) THEN
         Line = 
     > 'ERROR IN ZErMsg -- INVALID ERROR NUMBER ({-}) OR LEVEL ({-})'
cccc        call SWritI ( Line, NERR )
cccc        call SWritI ( Line, LEVEL )
cccc        call ZError ( Line )
cccc        call ZClose ( 999 )
         stop
      ENDIF
C
C       ANNOUNCE THE NAMES OF THE LIBRARY AND SUBROUTINE BY BUILDING A
C       MESSAGE IN CHARACTER VARIABLE TEMP 
C       AND SENDING IT OUT. 
C
      Line = LIBRAR(1:IndexR(LIBRAR))//'/'//SUBROU(1:IndexR(SUBROU))
     >       //'({-}): '//MESSG
cccc     call SWritI ( Line, NERR )
cccc     call ZError ( Line )
c
      IF ( LEVEL .gt. 1 ) THEN
cccc       call ZError ( 'Error is fatal, stopping' )
cccc       call ZClose ( 999 )
        stop
      END IF
c
      RETURN
      END