basic gps program

local arg = { ... }
local xcord=tonumber(arg[1])
local ycord=tonumber(arg[2])
local zcord=tonumber(arg[3])

if  arg[1]==nil
    or
    arg[2]==nil
    or
    arg[3]==nil then
    print("gps <x> <y> <z>")
    return
end

function locate()
    g = vector.new(gps.locate(2))
    turtle.forward()
    g2 = vector.new(gps.locate(2))
    turtle.back()
    if g.x == g2.x then
        if g.y > g2.y then
            turtle.turnLeft()
            turtle.turnLeft()
        end
    else
        if g.x > g2.x then
            turtle.turnLeft()
        else
            turtle.turnRight()
        end
    end
end

function calc()
    xmove = xcord - g.x
    if xmove < 0 then xmove=xmove*(-1) end
    ymove = ycord - g.y
    if ymove < 0 then ymove=ymove*(-1) end
    zmove = zcord - g.z
    if zmove < 0 then zmove=zmove*(-1) end
end

function move()
    if xcord ~= g.x then
        if xcord < g.x then
            turtle.turnRight()
            for i=1,xmove do
                turtle.forward()
            end
            turtle.turnLeft()
        else
            turtle.turnLeft()
            for i=1,xmove do
                turtle.forward()
            end
            turtle.turnRight()
        end
    end
    if ycord ~= g.y then
        if ycord > g.y then
            for i=1,ymove do
                turtle.forward()
            end
        else
            turtle.turnLeft()
            turtle.turnLeft()
            for i=1,ymove do
                turtle.forward()
            end
            turtle.turnLeft()
            turtle.turnLeft()
        end
    end
    if zcord ~= g.z then
        if zcord < g.z then
            for i=1,zmove do
                turtle.down()
            end
        else
            for i=1,zmove do
                turtle.up()
            end
        end
    end
end

locate()
calc()
move()