import { default } from "https://deno.land/x/simplestatistics@v7.8.3/src/error_function.js";
The errorFunction(x/(sd * Math.sqrt(2))) is the probability that a value in a
normal distribution with standard deviation sd is within x of the mean.
This function returns a numerical approximation to the exact value. It uses Horner's method to evaluate the polynomial of τ (tau).