Module:Exponential search: Difference between revisions
From Vigyanwiki
Template>Mr. Stradivarius (change names after page move) |
Template>Mr. Stradivarius (specify a lower bound of 0 initially so that we don't have to do it on every recursion) |
||
| Line 22: | Line 22: | ||
else | else | ||
upper = i | upper = i | ||
i = midPoint(lower, upper) | i = midPoint(lower, upper) | ||
return search(testFunc, i, lower, upper) | return search(testFunc, i, lower, upper) | ||
| Line 42: | Line 41: | ||
return nil | return nil | ||
end | end | ||
return search(testFunc, init) | return search(testFunc, init, 0, nil) | ||
end | end | ||
Revision as of 19:06, 25 February 2015
Documentation for this module may be created at Module:Exponential search/doc
-- This module provides a generic exponential search algorithm.
local checkType = require('libraryUtil').checkType
local floor = math.floor
local function midPoint(lower, upper)
return floor(lower + (upper - lower) / 2)
end
local function search(testFunc, i, lower, upper)
if testFunc(i) then
if i + 1 == upper then
return i
end
lower = i
if upper then
i = midPoint(lower, upper)
else
i = i * 2
end
return search(testFunc, i, lower, upper)
else
upper = i
i = midPoint(lower, upper)
return search(testFunc, i, lower, upper)
end
end
return function (testFunc, init)
checkType('Exponential search', 1, testFunc, 'function')
checkType('Exponential search', 2, initNum, 'number', true)
if init and (init < 1 or init ~= floor(init) or init == math.huge) then
error(string.format(
"invalid init value '%s' detected in argument #2 to " ..
"'Exponential search' (init values must be a positive integer)",
tostring(init)
), 2)
end
init = init or 1
if not testFunc(1) then
return nil
end
return search(testFunc, init, 0, nil)
end
