C DSCAL     SOURCE    CHAT      06/03/29    21:18:55     5360           
      SUBROUTINE DSCAL(N,DA,DX,INCX)
      IMPLICIT INTEGER(I-N)
      IMPLICIT REAL*8 (A-H,O-Z)
C     
C     SCALES A VECTOR BY A CONSTANT.
C         x <- ax
C     USES UNROLLED LOOPS FOR INCREMENT EQUAL TO ONE.
C     JACK DONGARRA, LINPACK, 3/11/78
C     MODIFIED 3/93 TO RETURN IF INCX .LE.0.
C     MODIFIED 12/3/93, ARRAY(1) DECLARATIONS CHANGED TO ARRAY(*)
C     
C     modified 5/11/98 double precision -> real*8
C                      no unrolled loops : compiler can do that
C                      added error handling
C     
-INC CCOPTIO
C     
      REAL*8 DA,DX(*)
      INTEGER I,INCX,N,NINCX
C     
      IF( N.LE.0 .OR. INCX.LE.0 ) GOTO 9999
      IF(INCX.NE.1) THEN
C     
C        CODE FOR INCREMENT NOT EQUAL TO 1
C     
         NINCX = N*INCX
         DO 10 I = 1,NINCX,INCX
            DX(I) = DA*DX(I)
 10      CONTINUE
      ELSE
C     
C        CODE FOR INCREMENT EQUAL TO 1
C     
         DO 30 I = 1,N
            DX(I) = DA*DX(I)
 30      CONTINUE
      ENDIF
C     
C     Normal termination
C     
      RETURN
C     
C     Error handling
C     
 9999 CONTINUE
      WRITE(IOIMP,*) 'dimension or increment lower than 1 transmitted'
      WRITE(IOIMP,*) 'to subroutine dscal : nothing done'
      call erreur(21)
      RETURN
C     
C     End of DSCAL
C     
      END