HP Forums

can anyone shed any light on how the HP 12C does date calculations?

not how to do them, I get that. I am curious how this might have been achieved on a calculator that has such limited ROM space. what type of programming would yield these features?

the fact it even returns day of the week, and has a large date range it supports is a marvel to me.

I don't know the specific algorithms used by the 12C, but compared to the other functionality in that calculator, date calculations are pretty easy. Take a look at the greg2jd and jd2greg functions here: https://fossies.org/linux/free42/common/...mmands7.cc (lines 207-233)

(04-24-2019 04:17 PM)Thomas Okken Wrote: [ -> ]I don't know the specific algorithms used by the 12C, but compared to the other functionality in that calculator, date calculations are pretty easy. Take a look at the greg2jd and jd2greg functions here: https://fossies.org/linux/free42/common/...mmands7.cc (lines 207-233)

thank you! I find it amazing that so much can be done in so little ROM space. I agree it is not that hard, but it is impressive anyway.

(04-24-2019 03:50 PM)detron Wrote: [ -> ]how the HP 12C does date calculations?

In the Manual on Page 187 maybe?!
Or you want to know it in machine code level?

Csaba