Script to test performance of functions

speed.lua

Position = {}
function Position.to_table(pos_arr)
    --fail_if_missing(pos_arr, "missing position argument")

    if #pos_arr == 2 then
        return { x = pos_arr[1], y = pos_arr[2] }
    end
    return pos_arr
end

function Position.distance_squared(pos1, pos2)
    pos1 = Position.to_table(pos1)
    pos2 = Position.to_table(pos2)
    local axbx = pos1.x - pos2.x
    local ayby = pos1.y - pos2.y
    return axbx * axbx + ayby * ayby
end

--local abs = math.abs
function Position.manhattan_distance(pos1, pos2)
    pos1 = Position.to_table(pos1)
    pos2 = Position.to_table(pos2)
    return math.abs(pos2.x - pos1.x) + math.abs(pos2.y - pos1.y)
end

local function printf(...)
    io.write(string.format(...))
end
local socket = require 'socket'

local tbl = {}
for j=1,160 do
    tbl[j] = {x=j,y=j+2}
end
local testPos = {x = 9001, y = -1337}
for loops=0,10000,100 do
    --for loops=0,100000,1000 do
    printf("%6d loops ",loops)
    local t0=socket.gettime()
    for i=1,loops do
        for _, pos in pairs(tbl) do
            Position.distance_squared(testPos, pos)
        end
    end

    local t1=socket.gettime()
    local m = (t1-t0)
    --if t1>t0 then  break end
    t0=socket.gettime()
    for i=1,loops do
        for _, pos in pairs(tbl) do
            Position.manhattan_distance(testPos, pos)
        end
    end
    t1=socket.gettime()
    local a = (t1-t0)
    printf(" c=%9.6f ms", (m-a)*1000)
    printf(" squared=%9.3f ms ",m*1000)
    printf(" manhattan=%9.3f ms\n",a*1000)
end