return {

toPrecisionNative = (function(d)

return function(n)

-- JS toPrecision(d) keeps d SIGNIFICANT digits (switching to exponent

-- form when needed); %f fixes d digits after the point, which is wrong

-- for every input. %g is the significant-digit specifier.

return string.format("%." .. tostring(d) .. "g", n)

end

end),

toFixedNative = (function(d) return function(n) return string.format("%." .. tostring(d) .. "f", n) end end),

toExponentialNative = (function(d)

return function(n)

-- C %e zero-pads the exponent to >=2 digits (e+03); JS toExponential

-- uses the minimal number of exponent digits (e+3). Strip one leading

-- zero from a single-digit exponent, leaving e+12 intact.

local s = string.format("%." .. tostring(d) .. "e", n)

return (s:gsub("([eE][%-+])0(%d)$", "%1%2"))

end

end),

toString = (function(num)

-- JS spells the non-finite values "Infinity"/"-Infinity"/"NaN"; Lua's

-- tostring gives "inf"/"-inf"/"nan"/"-nan". (Finite values keep Lua's

-- %.14g formatting, which is not the JS shortest-round-trip form.)

if num ~= num then return "NaN" end

if num == math.huge then return "Infinity" end

if num == -math.huge then return "-Infinity" end

return tostring(num)

end)

}