/[ascend]/trunk/blas/idamax.f
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Fri Oct 29 20:54:12 2004 UTC (15 years, 5 months ago) by aw0a
File size: 1115 byte(s)
Setting up web subdirectory in repository
1 aw0a 1 C idamax.f
2     C is freely available from netlib. It is not subject to any GNU License
3     C set by the authors of the ASCEND math programming system.
4     C $Date: 1996/04/30 18:14:08 $ $Revision: 1.1.1.1 $
5     C
6     integer function idamax(n,dx,incx)
7     c
8     c finds the index of element having max. absolute value.
9     c jack dongarra, linpack, 3/11/78.
10     c modified to correct problem with negative increment, 8/21/90.
11     c
12     double precision dx(*),dmax
13     integer i,incx,ix,n
14     c
15     idamax = 0
16     if( n .lt. 1 ) return
17     idamax = 1
18     if(n.eq.1)return
19     if(incx.eq.1)go to 20
20     c
21     c code for increment not equal to 1
22     c
23     ix = 1
24     if(incx.lt.0)ix = (-n+1)*incx + 1
25     dmax = dabs(dx(ix))
26     ix = ix + incx
27     do 10 i = 2,n
28     if(dabs(dx(ix)).le.dmax) go to 5
29     idamax = i
30     dmax = dabs(dx(ix))
31     5 ix = ix + incx
32     10 continue
33     return
34     c
35     c code for increment equal to 1
36     c
37     20 dmax = dabs(dx(1))
38     do 30 i = 2,n
39     if(dabs(dx(i)).le.dmax) go to 30
40     idamax = i
41     dmax = dabs(dx(i))
42     30 continue
43     return
44     end

john.pye@anu.edu.au
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