```01:       DOUBLE COMPLEX FUNCTION ZDOTC(N,ZX,INCX,ZY,INCY)
02: *     .. Scalar Arguments ..
03:       INTEGER INCX,INCY,N
04: *     ..
05: *     .. Array Arguments ..
06:       DOUBLE COMPLEX ZX(*),ZY(*)
07: *     ..
08: *
09: *  Purpose
10: *  =======
11: *
12: *  ZDOTC forms the dot product of a vector.
13: *
14: *  Further Details
15: *  ===============
16: *
17: *     jack dongarra, 3/11/78.
18: *     modified 12/3/93, array(1) declarations changed to array(*)
19: *
20: *  =====================================================================
21: *
22: *     .. Local Scalars ..
23:       DOUBLE COMPLEX ZTEMP
24:       INTEGER I,IX,IY
25: *     ..
26: *     .. Intrinsic Functions ..
27:       INTRINSIC DCONJG
28: *     ..
29:       ZTEMP = (0.0d0,0.0d0)
30:       ZDOTC = (0.0d0,0.0d0)
31:       IF (N.LE.0) RETURN
32:       IF (INCX.EQ.1 .AND. INCY.EQ.1) GO TO 20
33: *
34: *        code for unequal increments or equal increments
35: *          not equal to 1
36: *
37:       IX = 1
38:       IY = 1
39:       IF (INCX.LT.0) IX = (-N+1)*INCX + 1
40:       IF (INCY.LT.0) IY = (-N+1)*INCY + 1
41:       DO 10 I = 1,N
42:           ZTEMP = ZTEMP + DCONJG(ZX(IX))*ZY(IY)
43:           IX = IX + INCX
44:           IY = IY + INCY
45:    10 CONTINUE
46:       ZDOTC = ZTEMP
47:       RETURN
48: *
49: *        code for both increments equal to 1
50: *
51:    20 DO 30 I = 1,N
52:           ZTEMP = ZTEMP + DCONJG(ZX(I))*ZY(I)
53:    30 CONTINUE
54:       ZDOTC = ZTEMP
55:       RETURN
56:       END
57: ```