(50g) Normal Distribution

[John Keith]

So I have looked at the HP-67 code for Z(x) (subroutine 'E') and I believe this is the RPL equivalent:

Code:


\<< DUP IP SQ 2. / NEG EXP OVER IP PICK3 FP * EXP / SWAP FP SQ EXP \v/ / .3989422804028 *
\>>

where the in-line constant is SQRT(1/(2*pi)).

I tried both the above code and my original prog with an input of -10 and the results differ by only one ULP. I am clearly not an expert on either statistics or the HP-67 so I may be missing something here but I don't see an advantage for the more involved program above.