HP Forum Archive 01

[ Return to Index | Top of Index ]

HP21 calculation accuracy Message #1 Posted by Ian Hoogeboom on 18 July 1999, 3:57 p.m. Hello, I bought an non-working HP21 at a flee market, but after cleaning it's interior it works fine... I think. It's not so accurate (anymore), 2yx10 results in 1023.999999 instead of 1024 (all yx functions are not correct). Functions like tan 89.9995 result in 114585.0362 instead of 114591.559. Is this normal as this machine is more than 20 years old or is there something broken in the calculation part of it? Thank you in advance, Ian Hoogeboom.

Re: HP21 calculation accuracy Message #2 Posted by Mike Sebastian on 18 July 1999, 5:57 p.m., in response to message #1 by Ian Hoogeboom Early HPs, including your HP-21 only computed results to ten digits, with no guard digits. Modern HPs and many other modern calculators compute results to at least 12 digits, then round to ten digits. Your calculator is working correctly. The results you are observing are consistent with calculators of that era.

Re: HP21 calculation accuracy Message #3 Posted by Ian Hoogeboom on 19 July 1999, 4:12 a.m., in response to message #2 by Mike Sebastian Mike, Thank you for your reaction! Kind regards, Ian Hoogeboom.

[ Return to Index | Top of Index ]

Go back to the main exhibit hall