/[ascend]/trunk/blas/idamax.f
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Contents of /trunk/blas/idamax.f

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Revision 1 - (show annotations) (download)
Fri Oct 29 20:54:12 2004 UTC (15 years, 8 months ago) by aw0a
File size: 1115 byte(s)
Setting up web subdirectory in repository
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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