SIGMA(N:0:100:1:FACT(N))-X speed test on the 17BII+

[Bob Wang]

The HP 17BII+ has 6 times the memory of the 17B, 17BII, 19B, and 19BII, BUT, among other deficiencies, it is up to 18 times slower than my 10 year-old 19B running Tony Hutchins' excellent Black-Scholes formula: Re: Black-Scholes for 17BII+ with 12 Digit Accuracy

Here is a simple equation to enter into 17BII+s to check if HP removes this new "feature" in a future ROM revision:

SIGMA(N:0:100:1:FACT(N))-X

Enter guesses of 0 and 1 into X, i.e. type 0, hit X, type 1, hit X, then hit X to solve:

9.42690016837E157 in 5.25 seconds on the 19B and 19BII

9.42690016837E157 in 32.5 seconds on the 17BII+

The summation function "SIGMA" is found by pressing "ALPHA", "OTHER", then "MORE".

Bob