integer function idmaxf(n,dx,incx)

c

c     finds the index of element having max. value.

c     jack dongarra, linpack, 3/11/78.

c     modified 3/93 to return if incx .le. 0.

c     modified 12/3/93, array(1) declarations changed to array(*)

c

      double precision dx(*),dmax

      integer i,incx,ix,n

c

      idmaxf = 0

      if( n.lt.1 .or. incx.le.0 ) return

      idmaxf = 1

      if(n.eq.1)return

      if(incx.eq.1)go to 20

c

c        code for increment not equal to 1

c

      ix = 1

      dmax = dx(1)

      ix = ix + incx

      do 10 i = 2,n

         if(dx(ix).le.dmax) go to 5

         idmaxf = i

         dmax = dx(ix)

    5    ix = ix + incx

   10 continue

      return

c

c        code for increment equal to 1

c

   20 dmax = dx(1)

      do 30 i = 2,n

         if(dx(i).le.dmax) go to 30

         idmaxf = i

         dmax = dx(i)

   30 continue

      return

      end