CODEWITHSUNDEEP
lua
JV I
JV I

Reputation: 31

How do I type an arc tangent in lua 5.4 if the math.atan2 is?

I'm trying to use the math.library on Lua (version 5.4) and I tried to use the math.atan2 here:

math.randomseed (os.time())

local Player_x, Player_y = 400,300
local Enemy_x = math.random (0,800)
local Enemy_y = math.random (0,600)
local angle = math.atan2((Enemy_y - Player_y), (Enemy_x - Player_x))
local angle_degree = math.deg (angle)


print (Enemy_x..","..Enemy_y)
print ("The angle from Enemy to the Player: "..angle_degree.." degree.")

But when I tried to put run on my Visual Studio Code, it said that it was "discontinued" and deprecated. Is there a sort of way to fix this problem or is there a simple substitute of this situation?

Upvotes: 3

Views: 5928

Answers (3)

yuta y
yuta y

Reputation: 166

the range of atan() is pi/2(up) to -pi/2(down) wich is half the circle atan2() is pi to -pi wich is the whole circle

if you only use tan a extra value has to be added on

angle = math.atan((Enemy_y-Player_y)/(Enemy_x-Player_x));
if(Enemy_x<= Player_x and angle < 0)then--4th qudrent
    angle = (2*math.pi) + angle;
elseif(angle < 0) then--2nd qutial
    angle = math.pi+angle;
elseif(angle >= 0 and Enemy_x > Player_x)then
    angle = angle + (math.pi);--3rth
end

x increases ->

Upvotes: 0

user1542465
user1542465

Reputation: 43

Be aware that math.atan is not a drop-in replacement for math.atan2. math.atan2(2,2) ==> 0.7859 vs math.atan(2,2) ==> 1.1071 Whatever the difference is: they're not the same. – Ian Boyd

For anyone running into this like me: Make sure you are actually using lua 5.3 or above. In 5.2 the second argument is simply ignored, so writing math.atan(2, 2) is equal to writing math.atan(2), hence the difference.

Upvotes: 3

Piglet
Piglet

Reputation: 28974

math.atan2 was deprecated in Lua 5.3

https://www.lua.org/manual/5.3/manual.html#8.2

The following functions were deprecated in the mathematical library: atan2, cosh, sinh, tanh, pow, frexp, and ldexp. You can replace math.pow(x,y) with x^y; you can replace math.atan2 with math.atan, which now accepts one or two arguments; ...

local angle = math.atan((Enemy_y - Player_y), (Enemy_x - Player_x))

Upvotes: 5

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