share/lapack/blas/fortran/icamax.f

   1       integer function icamax(n,cx,incx)
   2 c
   3 c     finds the index of element having max. absolute value.
   4 c     jack dongarra, linpack, 3/11/78.
   5 c     modified 3/93 to return if incx .le. 0.
   6 c     modified 12/3/93, array(1) declarations changed to array(*)
   7 c
   8       complex cx(*)
   9       real smax
  10       integer i,incx,ix,n
  11       complex zdum
  12       real cabs1
  13       cabs1(zdum) = abs(real(zdum)) + abs(aimag(zdum))
  14 c
  15       icamax = 0
  16       if( n.lt.1 .or. incx.le.0 ) return
  17       icamax = 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       smax = cabs1(cx(1))
  25       ix = ix + incx
  26       do 10 i = 2,n
  27          if(cabs1(cx(ix)).le.smax) go to 5
  28          icamax = i
  29          smax = cabs1(cx(ix))
  30     5    ix = ix + incx
  31    10 continue
  32       return
  33 c
  34 c        code for increment equal to 1
  35 c
  36    20 smax = cabs1(cx(1))
  37       do 30 i = 2,n
  38          if(cabs1(cx(i)).le.smax) go to 30
  39          icamax = i
  40          smax = cabs1(cx(i))
  41    30 continue
  42       return
  43       end