-- This file:
--   http://angg.twu.net/LUA/BinarySearch1.lua.html
--   http://angg.twu.net/LUA/BinarySearch1.lua
--           (find-angg "LUA/BinarySearch1.lua")
-- Author: Eduardo Ochs <eduardoochs@gmail.com>
--
-- (defun e () (interactive) (find-angg "LUA/BinarySearch1.lua"))

BinarySearch = Class {
  type    = "BinarySearch",
  __index = {
    middle = function (bs) return (bs.a + bs.b) / 2 end,
    newinterval = function (bs, newa, newb)
        return BinarySearch {a=newa, b=newb, f=bs.f}
      end,
    left  = function (bs) return bs:newinterval(bs.a, bs:middle()) end,
    right = function (bs) return bs:newinterval(bs:middle(), bs.b) end,
    halve = function (bs, ntimes)
        for i=1,ntimes do
          if bs.f(bs:middle()) == bs.f(bs.a)
          then bs = bs:right()
          else bs = bs:left()
          end
        end
        return bs
      end,
  },
}


--[[
* (eepitch-lua51)
* (eepitch-kill)
* (eepitch-lua51)
dofile "BinarySearch1.lua"

bs = BinarySearch {a=0, b=10, f = function (x) return x^2 < 2 end}
= bs:halve(10):middle()
= bs:halve(100):middle()

--]]




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