```      INTEGER FUNCTION IZAMAX(N,ZX,INCX)
*     .. Scalar Arguments ..
INTEGER INCX,N
*     ..
*     .. Array Arguments ..
DOUBLE COMPLEX ZX(*)
*     ..
*
*  Purpose
*  =======
*
*     finds the index of element having max. absolute value.
*     jack dongarra, 1/15/85.
*     modified 3/93 to return if incx .le. 0.
*     modified 12/3/93, array(1) declarations changed to array(*)
*
*
*     .. Local Scalars ..
DOUBLE PRECISION SMAX
INTEGER I,IX
*     ..
*     .. External Functions ..
DOUBLE PRECISION DCABS1
EXTERNAL DCABS1
*     ..
IZAMAX = 0
IF (N.LT.1 .OR. INCX.LE.0) RETURN
IZAMAX = 1
IF (N.EQ.1) RETURN
IF (INCX.EQ.1) GO TO 20
*
*        code for increment not equal to 1
*
IX = 1
SMAX = DCABS1(ZX(1))
IX = IX + INCX
DO 10 I = 2,N
IF (DCABS1(ZX(IX)).LE.SMAX) GO TO 5
IZAMAX = I
SMAX = DCABS1(ZX(IX))
5     IX = IX + INCX
10 CONTINUE
RETURN
*
*        code for increment equal to 1
*
20 SMAX = DCABS1(ZX(1))
DO 30 I = 2,N
IF (DCABS1(ZX(I)).LE.SMAX) GO TO 30
IZAMAX = I
SMAX = DCABS1(ZX(I))
30 CONTINUE
RETURN
END

```