StarCursor nan(ind)

[biokiwi]

hi i used the addon StarCursor for some time now and wanted to debug it since it has some issues after the prepatch.

the bug happens sometimes after a loadingscreen and corrupts some calculationand turns a Number into nan(ind) (NotANumber) and freezes the cursor animation. no lua error

the line " print(tostring((-1)^.5)); " also triggers the bug but i dont understand how this NaN affects the other calculations

This would be a fix but i stil would not understand what happens:
if (speed<0 and speed>0) then speed=0; end

The code:

local x,y,speed = 0,0,0; -- cursor (SnowfallCursor by Dyan)
local CursorFrame = CreateFrame("Frame", "CursorFrame", UIParent);
CursorFrame:SetFrameStrata("TOOLTIP");
CursorFrame.texture = CursorFrame:CreateTexture();
CursorFrame.texture:SetTexture([[Interface\Cooldown\star4]]);
CursorFrame.texture:SetBlendMode("ADD");
CursorFrame.texture:SetAlpha(0.5);
CursorFrame:SetScript( "OnUpdate", function(frame,elapsed)
local dX = x;
local dY = y;
x, y = GetCursorPosition();
dX = x - dX;
dY = y - dY;
print(tostring((-1)^.5));
local weight = 2048 ^ -elapsed;
speed = math.min(weight * speed + (1 - weight) * math.sqrt(dX * dX + dY * dY) / elapsed, 1024);
print(speed);
local size = speed / 6 - 50;
if ( size > 0) then
local scale = UIParent:GetEffectiveScale();
CursorFrame.texture:SetHeight(size);
CursorFrame.texture:SetWidth(size);
CursorFrame.texture:SetPoint("CENTER", UIParent, "BOTTOMLEFT", (x + 0.5 * dX) / scale, (y + 0.5 * dY) / scale);
CursorFrame.texture:Show();
else
CursorFrame.texture:Hide();
end
end);