add link

1 files changed, 1 insertions, 0 deletions

diff --git a/main.lua b/main.lua
index ecac412..ff212f5 100644
--- a/main.lua
+++ b/main.lua
@@ -44,6 +44,7 @@ function love.wheelmoved(x,y)
 end
 
 local function catenary0(x1,y1,x2,y2)
+	-- https://math.stackexchange.com/a/3557768
 	y1 = -y1
 	y2 = -y2
 	local dx = x2-x1