Accurate Normal Distribution for the HP67/97

[John Keith]

That is a neat program, although I can only begin to understand it. I tried it on the HP 50 and while it is a smaller and faster program than the 2-Exp program in this thread, it is not as accurate if the mean and variance are other than 0 and 1 respectively. For "standard" values of x it is accurate to +/- 1 ULP.

My implementation is straightforward except for the second line,
double x = (float) z;
which turned into -6 RND i.e. round to 6 digits.

I did not experience any underflow, just a less accurate result.