Discrepancy between DM42 and Hp 50g

Discussion around the Swiss Micros DM42 calculator.
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jvanoort
Posts: 16
Joined: Wed Feb 24, 2021 1:30 pm

Discrepancy between DM42 and Hp 50g

Post by jvanoort »

Hi all,

I posted this on the HP forum as well, but since it also relates to the DM42 I thought I’d ask here too.
I hope you guys don’t mind.

Today I calculated the energy flux from the sun using the Stefan Bolzmann equation:
EF = sT^4. So as follows:

5777
4
Y^X
5.67E-8
*

On my DM42 and WP34s the result is: 63152788.1436
On my HP 35s and 50g however the result is: 63152788.1439

On my computer Python agrees with my DM42 and WP34s

All display settings were the same on all machines.

What might be causing this difference?
Joe Horn
Posts: 32
Joined: Thu Oct 04, 2018 2:10 am

Re: Discrepancy between DM42 and Hp 50g

Post by Joe Horn »

Here's what I replied to your question on the MoHPC forum:

The 35s and 50g (and most other HP models which use BCD math with a 12-digit mantissa) round all intermediate results to 12 significant digits. You'll get the same result on your DM42 if you put it into SCI 11 mode and execute RND after each operation, which is essentially what the 35s and 50g do automatically.
jvanoort
Posts: 16
Joined: Wed Feb 24, 2021 1:30 pm

Re: Discrepancy between DM42 and Hp 50g

Post by jvanoort »

Hi Joe, I did as you suggested and got the same result indeed. Thank you!
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