# HP Forums

You're currently viewing a stripped down version of our content. View the full version with proper formatting.
Similar to my No RPL? question, this is just based on reading the User Guide. One of the features I use fairly heavily on the HP50 is the built-in arbitrary precision large number math (i.e., exact mode). Does this exist on the Prime?

There's reference to this being available in the CAS but a somewhat ominous statement that calculations done in the Home view often yield numerical approximations. Are exact numbers not a first class citizen on the Prime?

- John
Hello!

In CAS mode ---> Settings you can check "[ ] EXACT".....

Or you refer to another topic?
Yes, I saw that, but what it appears might be implied is that exact numbers are not supported uniformly across the whole calculator. As a trivial example, when I enter (on my HP50g)
Code:
2 [Enter] 6 ÷
then I expect to see the result $$\frac{1}{3}$$ on the stack. If I need the numeric approximation, then it's just a keystroke away.

- John
(12-17-2013 04:25 PM)John R. Graham Wrote: [ -> ]Yes, I saw that, but what it appears might be implied is that exact numbers are not supported uniformly across the whole calculator. As a trivial example, when I enter (on my HP50g)
Code:
2 [Enter] 6 ÷
then I expect to see the result $$\frac{1}{3}$$ on the stack. If I need the numeric approximation, then it's just a keystroke away.

- John

In CAS Mode, 1/3 = $$\frac{1}{3}$$ on the stack.

In Home Mode, 1/3 = 0.33333333333 on the stack.

CAS Mode and Home Mode works different, obviusly
Or, in CAS:

2÷6 [Enter] enters 1/3 into history.

[Shift-Enter] puts .333 into history.

Except for RPN this seems like the same thing as the 50g.
Thanks. However, I kind of got off topic here for a moment. Is there a variable type that is manipulatable from PPL that will represent an exact arbitrary precision integer? The only reference I see to integers in the documentation are the binary numbers, which seem to be strictly limited in precision (just like they are on the HP50).

- John
(12-17-2013 05:48 PM)John R. Graham Wrote: [ -> ]Is there a variable type that is manipulatable from PPL that will represent an exact arbitrary precision integer? The only reference I see to integers in the documentation are the binary numbers, which seem to be strictly limited in precision (just like they are on the HP50).

Not in Home, which is like approximate mode on the 50g. Long integers are only available in CAS (which is like exact mode on the 50g), from which they can be stored in any CAS variable. So if you want to use them in a program, it must be a CAS program, not a "normal" program. My PDQ program (posted in the Prime Software section, see link below) is an example of this. It allows inputs of any length, and can generate "infinite precision" results such as fractions whose numerator and denominator are integers with more than 12 digits each.

PDQ with examples is here: http://www.hpmuseum.org/forum/thread-61.html

BUT WAIT! I just set a CAS variable equal to a large integer, then went back into Home, and tried ifactor (a CAS function) on it while in Home. It got the same full-accuracy result as ifactor gets in CAS! So variables containing long integers CAN be used with full accuracy in Home... but only if handled by CAS functions. Perhaps normal programs can use long integers too, if first saved in CAS variables? Maybe! This should be explored further.
Reference URL's
• HP Forums: https://www.hpmuseum.org/forum/index.php
• :