1: INTEGER FUNCTION IZAMAX(N,ZX,INCX)
2: * .. Scalar Arguments ..
3: INTEGER INCX,N
4: * ..
5: * .. Array Arguments ..
6: DOUBLE COMPLEX ZX(*)
7: * ..
8: *
9: * Purpose
10: * =======
11: *
12: * IZAMAX finds the index of element having max. absolute value.
13: *
14: * Further Details
15: * ===============
16: *
17: * jack dongarra, 1/15/85.
18: * modified 3/93 to return if incx .le. 0.
19: * modified 12/3/93, array(1) declarations changed to array(*)
20: *
21: * =====================================================================
22: *
23: * .. Local Scalars ..
24: DOUBLE PRECISION DMAX
25: INTEGER I,IX
26: * ..
27: * .. External Functions ..
28: DOUBLE PRECISION DCABS1
29: EXTERNAL DCABS1
30: * ..
31: IZAMAX = 0
32: IF (N.LT.1 .OR. INCX.LE.0) RETURN
33: IZAMAX = 1
34: IF (N.EQ.1) RETURN
35: IF (INCX.EQ.1) THEN
36: *
37: * code for increment equal to 1
38: *
39: DMAX = DCABS1(ZX(1))
40: DO I = 2,N
41: IF (DCABS1(ZX(I)).GT.DMAX) THEN
42: IZAMAX = I
43: DMAX = DCABS1(ZX(I))
44: END IF
45: END DO
46: ELSE
47: *
48: * code for increment not equal to 1
49: *
50: IX = 1
51: DMAX = DCABS1(ZX(1))
52: IX = IX + INCX
53: DO I = 2,N
54: IF (DCABS1(ZX(IX)).GT.DMAX) THEN
55: IZAMAX = I
56: DMAX = DCABS1(ZX(IX))
57: END IF
58: IX = IX + INCX
59: END DO
60: END IF
61: RETURN
62: END
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