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    1:       SUBROUTINE ZAXPY(N,ZA,ZX,INCX,ZY,INCY)
    2: *     .. Scalar Arguments ..
    3:       DOUBLE COMPLEX ZA
    4:       INTEGER INCX,INCY,N
    5: *     ..
    6: *     .. Array Arguments ..
    7:       DOUBLE COMPLEX ZX(*),ZY(*)
    8: *     ..
    9: *
   10: *  Purpose
   11: *  =======
   12: *
   13: *     ZAXPY constant times a vector plus a vector.
   14: *
   15: *  Further Details
   16: *  ===============
   17: *
   18: *     jack dongarra, 3/11/78.
   19: *     modified 12/3/93, array(1) declarations changed to array(*)
   20: *
   21: *  =====================================================================
   22: *
   23: *     .. Local Scalars ..
   24:       INTEGER I,IX,IY
   25: *     ..
   26: *     .. External Functions ..
   27:       DOUBLE PRECISION DCABS1
   28:       EXTERNAL DCABS1
   29: *     ..
   30:       IF (N.LE.0) RETURN
   31:       IF (DCABS1(ZA).EQ.0.0d0) RETURN
   32:       IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN
   33: *
   34: *        code for both increments equal to 1
   35: *
   36:          DO I = 1,N
   37:             ZY(I) = ZY(I) + ZA*ZX(I)
   38:          END DO
   39:       ELSE
   40: *
   41: *        code for unequal increments or equal increments
   42: *          not equal to 1
   43: *
   44:          IX = 1
   45:          IY = 1
   46:          IF (INCX.LT.0) IX = (-N+1)*INCX + 1
   47:          IF (INCY.LT.0) IY = (-N+1)*INCY + 1
   48:          DO I = 1,N
   49:             ZY(IY) = ZY(IY) + ZA*ZX(IX)
   50:             IX = IX + INCX
   51:             IY = IY + INCY
   52:          END DO
   53:       END IF
   54: *
   55:       RETURN
   56:       END