Voyagers and Scientific Notation Mode

[Eddie W. Shore]

This issue was brought to our attention by Alex Garza.

In SCI mode, when the number of decimal places are high, the number on the display is not rounded appropriately. Garza mentioned that this happens on the HP 15C.

Calculators used:
HP 15C CE: HP 15C Collector's Edition (2023)
HP 11C: HP 11C (1981)


45.55555555 -> R1

SCI 2
HP 15C CE: 4.56 01
HP 11C: 4.56 01

SCI 4
HP 15C CE: 4.5556 01
HP 11C: 4.5556 01

SCI 6
HP 15C CE: 4.555556 01
HP 11C: 4.555556 01

SCI 7, 8, 9
HP 15C CE: 4.555555 01
HP 11C: 4.555555 01


1234.56789 -> R2

SCI 2
HP 15C CE: 1.23 03
HP 11C: 1.23 03

SCI 4
HP 15C CE: 1.2346 03
HP 11C: 1.2346 03

SCI 6
HP 15C CE: 1.234568 03
HP 11C: 1.234568 03

SCI 7, 8, 9
HP 15C CE: 1.234567 03
HP 11C: 1.234567 03

pi -> R3

SCI 6
HP 15C CE: 3.141593 00
HP 11C: 3.141593 00

SCI 7, 8, 9
HP 15C CE: 3.141592 00
HP 11C: 3.141592 00


I think that the blank space plus the two-digit exponent is shown on top of the mantissa, but this is just my opinion and educated guess. We can use the RND (round to the fixed decimal setting) and the number rounds correctly.

[Brian Zilli]

I believe this is expected behavior: see pp. 58-59 of the 15c owner's handbook. Your understanding of what's happening appears to agree with that.

[Johnh]

When you ask for Sci 7 or more, that's more digits than it can display without looking for those extra mantissa numbers (f, prefix will show them momentarily). So i reckon its understandable behaviour, but it's good to be aware of it and thanks for pointing it out.

[agarza]

(11-04-2023 08:50 PM)Eddie W. Shore Wrote:  In SCI mode, when the number of decimal places are high, the number on the display is not rounded appropriately. Garza mentioned that this happens on the HP 15C.

This happens on the HP41C as well, and with ENG notation.

[Peet]

(11-04-2023 08:50 PM)Eddie W. Shore Wrote:  pi -> R3

SCI 6
HP 15C CE: 3.141593 00
HP 11C: 3.141593 00

SCI 7, 8, 9
HP 15C CE: 3.141592 00
HP 11C: 3.141592 00

SCI 6 shows the number rounded to the 6th decimal number
SCI 7 shows the number rounded to the 7th decimal number etc.

You can check this with the 41, which shows one more digit. So the difference on this one starts at sci 8.