HP35s Revisited Trig Quandary Bug # 2

[Paul Dale]

(02-17-2015 02:40 AM)MarkHaysHarris777 Wrote:  Quite true. Now, I have a question (and I'm not busting anyone in the chops, nor am I being trite. Would it be fair, in your estimation, for me to call the WP34s a 'trig dud,' because, in comparison, it is not able to calculate transcendental values as nearly accurately as pdeclib on my Droid phone?

The 34S gives sixteen correct digits in single precision mode here which was always our target -- 1 ULP was the goal rather than correctly rounded BTW. We know it isn't accurate in double precision mode -- this is documented in the manual. At least the 34S isn't worse than what came before.

I'm pretty sure I conned the "dud" term in the 35S bug list too It loses a lot more than two digits in the worst case. Anyway, feel free to call the 34S a dud too, it is only fair.

Quote:Is it not time, considering the fact that memory is relatively cheap and available, that we would permit the user to not only select the number of digits they will display, but also allow the user to configure the number of digits used internally for intermediate result calculation?

The memory is not available on the 30b hardware. We've used it all. There are some operations that fill the volatile RAM (some statistical functions and matrix operations). Non-volatile RAM has a couple of bits left so there'd be nowhere to store the extra state information. Flash isn't quite full but anything used reduces library space.

If we assume that memory were available, the task would be possible but wouldn't be easy. Several of the algorithms in the 34S are designed with the number of digits used in mind. The basic arithmetic and square root functions will work. Some of the other functions might, quite a few won't. Gamma e.g. uses a fixed series expansion which won't scale to arbitrary digit counts.

It would be possible to reimplement the internal functions that are limited but it would be a good chunk of work. Bringing in and using another decimal library would also be a possibility.


- Pauli