* SUBROUTINE MXVINV               ALL SYSTEMS                91/12/01
* PORTABILITY : ALL SYSTEMS
* 91/12/01 LU : ORIGINAL VERSION
*
* PURPOSE :
* CHANGE OF THE INTEGER VECTOR ELEMENT FOR THE CONSTRAINT ADDITION.
*
* PARAMETERS :
*  II  N  VECTOR DIMENSION.
*  IU  IX(N)  INTEGER VECTOR.
*  II  I  INDEX OF THE CHANGED ELEMENT.
*  II  JOB  CHANGE SPECIFICATION
*
      SUBROUTINE MXVINV(IX,I,JOB)
      INTEGER          I,JOB
      INTEGER          IX(*)
      IF ((IX(I).EQ.3.OR.IX(I).EQ.5) .AND. JOB.LT.0) IX(I) = IX(I) + 1
      IF ((IX(I).EQ.4.OR.IX(I).EQ.6) .AND. JOB.GT.0) IX(I) = IX(I) - 1
      IX(I) = -IX(I)
      RETURN
      END