In reply to dave_59:
I just try to provide a solution to have more smooth curve without hardcoded a/b/c/d array definition. with a/b/c/d fixed array, we can’t have a smooth curve unless you want to define huge array.
if the user provides bad std/mean/seed, it might break $dist_normal for sure.
everything can be fixed, e.g. just put an iteration_count in while loop to catch this issue.