-- Inverse error function -- https://dlmf.nist.gov/7.17 -- https://mathworld.wolfram.com/InverseErf.html -- https://oeis.org/A092676 Ainverf = (1, 1, 7, 127, 4369, 34807, 20036983, 2280356863, 49020204823, 65967241200001, 15773461423793767, 655889589032992201, 94020690191035873697, 655782249799531714375489) -- https://oeis.org/A092677 Binverf = (1, 3, 30, 630, 22680, 178200, 97297200, 10216206000, 198486288000, 237588086736000, 49893498214560000, 1803293578326240000, 222759794969712000000, 1329207696584271504000000) Cinverf = float(Ainverf / Binverf) Dinverf = sqrt(float(pi)) / 2 Finverf(x,k) = sum(k, 1, 14, Cinverf[k] (Dinverf x)^(2 k - 1)) -- errors for x = -1 to 1 for(k, -10, 10, x = k / 10.0, print(x, erf(Finverf(x)) - x)) draw(Finverf(x),x) Run