diff options
Diffstat (limited to 'spirals.lua')
| -rw-r--r-- | spirals.lua | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/spirals.lua b/spirals.lua new file mode 100644 index 0000000..0a8dea1 --- /dev/null +++ b/spirals.lua @@ -0,0 +1,17 @@ +av, sn = math.abs, function(s) return s~=0 and s/av(s) or 0 end +function sindex(y, x) -- returns the value at (x, y) in a spiral that starts at 1 and goes outwards + if y == -x and y >= x then return (2*y+1)^2 end + local l = math.max(av(y), av(x)) + return (2*l-1)^2+4*l+2*l*sn(x+y)+sn(y^2-x^2)*(l-(av(y)==l and sn(y)*x or sn(x)*y)) -- OH GOD WHAT +end + +function spiralt(side) + local ret, start, stop = {}, math.floor((-side+1)/2), math.floor((side-1)/2) + for i = 1, side do + ret[i] = {} + for j = 1, side do + ret[i][j] = side^2 - sindex(stop - i + 1,start + j - 1) --moves the coordinates so (0,0) is at the center of the spiral + end + end + return ret +end |