koreader/frontend/optmath.lua

--[[
Simple math helper function
]]--

local Math = {}

function Math.roundAwayFromZero(num)
	if num > 0 then
		return math.ceil(num)
	else
		return math.floor(num)
	end
end

function Math.round(num)
	return math.floor(num + 0.5)
end

function Math.oddEven(number)
	if number % 2 == 1 then
		return "odd"
	else
		return "even"
	end
end

local function tmin_max(tab, func, op)
	if #tab == 0 then return nil, nil end
	local index, value = 1, tab[1]
    for i = 2, #tab do
    	if func then
    		if func(value, tab[i]) then
	        	index, value = i, tab[i]
	        end
	    elseif op == "min" then
	    	if value > tab[i] then
	    		index, value = i, tab[i]
	    	end
	    elseif op == "max" then
	   		if value < tab[i] then
	    		index, value = i, tab[i]
	    	end
	    end
    end
    return index, value
end

--[[
Return the minimum element of a table.
The optional argument func specifies a one-argument ordering function.
]]--
function Math.tmin(tab, func)
	return tmin_max(tab, func, "min")
end

--[[
Return the maximum element of a table.
The optional argument func specifies a one-argument ordering function.
]]--
function Math.tmax(tab, func)
	return tmin_max(tab, func, "max")
end

return Math