HP Forums

How do you convert decimals to fractions?

Is there anyway to reduce the autopower off time? It's too long.

How do you erase all of the data (all of the previous calculations and notebook stuff)?? I think it is slowing my calculator down.

Thanks!

>How do you convert decimals to fractions?

->Q or ->QPI

>Is there anyway to reduce the autopower off time? It's too long.

RightShift On turns the machine off.

>How do you erase all of the data (all of the previous calculations and notebook stuff)?? I think it is slowing my calculator down.

RightShift BackArrow to clear stack.

If you'd like to change the auto time-off, store a hexadecimal number in a value named TOFF in your home directory.

#(sec*8192)d is the number, so for 15 seconds, it would be #122880d (15*8192). Default time is 5 minutes I think.

First off, be sure to have the HP 49g+ & 48gII_Advanced
User's Reference Manual; it's available from
this
HP page.

Also have a look at the
training
modules.

Quote:
How do you convert decimals to fractions?

Of course, for an exact conversion, you could consider the "real"
(decimal) number to be the numerator of a fraction with 1 as its
denominator, and multiply both the numerator and denominator by
whichever is the lowest power of 10 required to make the resulting
numerator an integer.

Other than that, for approximate conversions, you could try the
\->Q, \->Q\pi, or XQ commands.

Also try searches of http://www.hpcalc.org/ and
http://groups.google.com/group/comp.sys.hp48/ for programs
such as PDQ (or maybe PDQ1 or PDQ2) and DEC2FRAC.

Maybe read the training module entitled Working with
fractions.

Quote:
Is there anyway to reduce the autopower off time? It's too long.

Yes. With any 49 series, store a binary integer up to #FFFFFFFFh
(the largest 32-bit integer) in the reserved variable 'TOFF'. This
represents the number of ticks (1 second = 8192 ticks) of
inactivity before the calculator automatically turns off, with a
minimum of 5 seconds as a "safety net". For example, storing
#5A000h in TOFF results in a 45-second automatic timed OFF.

For a "never-off" mode, an alternative is to store a program that
doesn't include the OFF command in the reserved variable
'STARTOFF', which will be run whenever the automatic timed OFF
would occur, whether the default 5 minutes or as set by TOFF. But
note that STARTOFF won't by invoked by RightShift OFF, which
simply invokes the OFF command itself, unless you assign something
else to that keystroke.

Quote:
How do you erase all of the data (all of the previous calculations
and notebook stuff)?? I think it is slowing my calculator down.

?????

Do you mean how to clear the stack? RightShift CLEAR does that. Of
course that simply invokes the CLEAR command. Generally, clear the
stack either when you're sure that you're finished with a problem,
or just before starting a new problem.

If you mean how to purge variables, you can use the PURGE (or for
directories, PGDIR) command, or you can use the filer (LeftShift
FILES) to purge variables. To purge all variables from the current
directory, use the CLVAR command.

To clear memory entirely, press and hold [ON], [A], and [F] all
at the same time, then release [F] first, followed by the other
two keys, to get a TTRM (Try To Recover Memory?) screen.

Of course, all of this assumes that you have the 49 series in
"RPN" mode, not "ALG" mode.

Last but not least, for RPL models, you'd probably do better
searching the comp.sys.hp48 usenet group from
http://groups.google.com/advanced_search?, or if you can't
find the answer, post your question to the newsgroup.

Regards
James

Edited: 5 May 2007, 11:46 p.m.

PhysicsNerd

Happy HP User

Tim Wessman

James M. Prange (Michigan)