CVM Class Library  8.1
This C++ class library encapsulates concepts of vector and different matrices including square, band, symmetric and hermitian ones in Euclidean space of real and complex numbers.
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isamax.f
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1 c BLAS routine missing in ACML and some other implementations
2 
3  integer function isamax(n,sx,incx)
4 c
5 c finds the index of element having max. absolute value.
6 c jack dongarra, linpack, 3/11/78.
7 c modified 3/93 to return if incx .le. 0.
8 c modified 12/3/93, array(1) declarations changed to array(*)
9 c
10  real sx(*),smax
11  integer i,incx,ix,n
12 c
13  isamax = 0
14  if( n.lt.1 .or. incx.le.0 ) return
15  isamax = 1
16  if(n.eq.1)return
17  if(incx.eq.1)go to 20
18 c
19 c code for increment not equal to 1
20 c
21  ix = 1
22  smax = abs(sx(1))
23  ix = ix + incx
24  do 10 i = 2,n
25  if(abs(sx(ix)).le.smax) go to 5
26  isamax = i
27  smax = abs(sx(ix))
28  5 ix = ix + incx
29  10 continue
30  return
31 c
32 c code for increment equal to 1
33 c
34  20 smax = abs(sx(1))
35  do 30 i = 2,n
36  if(abs(sx(i)).le.smax) go to 30
37  isamax = i
38  smax = abs(sx(i))
39  30 continue
40  return
41  end
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