! 3.5.f90
! 14:00 2014-08-15
!
implicit none
character(10) :: keisen
integer :: i, m, n
real(8) :: eps, f, lambda, left, mid, r, right

r =   0.1
f = 100.0
m =  1
n = 15
i =  1
eps = 1.0e-4
left  = 0.0
right = 1.0
mid = (left + right) / 2.0
do while(abs(g(mid)) > eps )
  i = i + 1
  if(g(mid) > 0.0) then
    left = mid
  else
    right = mid
  end if
  mid = (left + right) / 2.0
end do
lambda = mid
write(*,'(a,f10.5,a,f10.6,a,i10)') 'lambda = ',lambda,', f(lambda) = ',g(lambda), ', i= ',i

stop

contains

function g(x)
  real(8) :: g
  real(8),intent(in) :: x
  g = f / (1.0 + x / m)**n + f * r / x * (1.0 - 1.0 / (1.0 + x / m)**n) - 1.05 * f
  return
end function g

end