Annotation of rpl/lapack/blas/idamax.f, revision 1.2
1.1 bertrand 1: INTEGER FUNCTION IDAMAX(N,DX,INCX)
2: * .. Scalar Arguments ..
3: INTEGER INCX,N
4: * ..
5: * .. Array Arguments ..
6: DOUBLE PRECISION DX(*)
7: * ..
8: *
9: * Purpose
10: * =======
11: *
12: * IDAMAX finds the index of element having max. absolute value.
13: *
14: * Further Details
15: * ===============
16: *
17: * jack dongarra, linpack, 3/11/78.
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: * .. Intrinsic Functions ..
28: INTRINSIC DABS
29: * ..
30: IDAMAX = 0
31: IF (N.LT.1 .OR. INCX.LE.0) RETURN
32: IDAMAX = 1
33: IF (N.EQ.1) RETURN
34: IF (INCX.EQ.1) GO TO 20
35: *
36: * code for increment not equal to 1
37: *
38: IX = 1
39: DMAX = DABS(DX(1))
40: IX = IX + INCX
41: DO 10 I = 2,N
42: IF (DABS(DX(IX)).LE.DMAX) GO TO 5
43: IDAMAX = I
44: DMAX = DABS(DX(IX))
45: 5 IX = IX + INCX
46: 10 CONTINUE
47: RETURN
48: *
49: * code for increment equal to 1
50: *
51: 20 DMAX = DABS(DX(1))
52: DO 30 I = 2,N
53: IF (DABS(DX(I)).LE.DMAX) GO TO 30
54: IDAMAX = I
55: DMAX = DABS(DX(I))
56: 30 CONTINUE
57: RETURN
58: END
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