WP 34S vs. DM42 decimal128 differences?

[Nigel (UK)]

(03-27-2018 06:10 AM)rkf Wrote:  Or do you compare the (exact) result of taking sin of a number, which is exactly pi rounded to 34 significant figures (thus to be expected in the ballpark around +/- 1E-34) with the result the calculator gives, and then -1.158028306006248941790250554076922E-34 itself is only correct to 17 figures? But that would be no problem at all for me.

I'm counting significant figures from the first non-zero digit - i.e., what you say above.

I agree that it isn't likely to be a problem in any real-world application of the calculator. However, given that the WP34S has a double-precision mode it would be nice if the result was also correct to this level of precision, so long as this can be done without breaking the calculator's behaviour elsewhere. If you calculate sin (3.1415926536) on the HP28S (for example) you will get an answer correct to 12 non-zero significant digits, and Pauli has already adjusted the WP34S code to get cos (pi/2) (which is a similar case) correct to 34 sf. Most of the time the trig functions are correct to this level of precision, so trying to bring sin (pi) up to the same standard isn't unreasonable.

I think it would be nice to fix it, if it can be fixed.

Nigel (UK)