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Fraction writing in RPN
Message #1 Posted by Shane Warner on 19 Nov 2006, 12:10 p.m.

I also just purchased a 50g. I have HP 33 and 32 and in both fraction writing is made simple by using the "." (decimal key) pushing it twice. Those (33 and 32) will keep the problem in fraction form all the way to the answer. Anyone know how to do this on the 50g? Thanks for your help. Shane Warner shane@helisphere.com

      
Re: Fraction writing in RPN
Message #2 Posted by John Smitherman on 19 Nov 2006, 1:06 p.m.,
in response to message #1 by Shane Warner

Hi Shane. Here's a link to an HP50G learning module on working with fractions:

http://h20331.www2.hp.com/Hpsub/downloads/50gWorking_with_fractions.pdf

Hopefully, this answer your question.

Regards,

John

            
Re: Fraction writing in RPN
Message #3 Posted by Shane Warner on 19 Nov 2006, 2:06 p.m.,
in response to message #2 by John Smitherman

Thanks John, I am still getting use to this calc. I will review this and see, but so far all the numbers are ataying on decimal form....

Thanks I will keep trying to adjust the settings.

Thanks Shane

            
Re: Fraction writing in RPN
Message #4 Posted by Rich Messeder (US) on 26 Nov 2006, 10:47 a.m.,
in response to message #2 by John Smitherman

I downloaded this file and noticed some puzzling items.

1. Some paragraphs refer to the HP48GII.
2. The CAS display at the top of p.3 show Approx checked, though the text says to uncheck it.
3. P. 3 specifies STD format, but I see fractions in FIX 2, for example.

Of course, I'm not familiar with the 48GII, so there mey ba a good reason for #1.

Rich

      
Re: Fraction writing in RPN
Message #5 Posted by Rich Messeder (US) on 19 Nov 2006, 5:04 p.m.,
in response to message #1 by Shane Warner

I found that the Mode~CAS~Numeric flag also needed to be unchecked.

Rich
To live in the past is to die in the present.
To learn from the past is to live in the future.

      
Re: Fraction writing in RPN
Message #6 Posted by Hal Bitton on 19 Nov 2006, 9:13 p.m.,
in response to message #1 by Shane Warner

Hi Shane,
I asked the same question when I got a 48G several months back, and if the 50G has similar functionality when using fractions (which I think it does) it's like this:
There is no dedicated "fraction mode" as on the 33S, but you can convert the number in stack level one to a fraction anytime by using symbolic mode (on the 48G left shift "SYMBOLIC", then the ">Q" softkey). If you want to see your work in fractional form all the way through, you can put your calculation in as an algebraic object using the equation writer, and then evaluate it (I think it evaluates back to a decimal, however). I suppose the concession to be derived from this is that the RPL machines impose no arbitrary limit on the size of the denominator like the 33S does (I think it's 4000). My 48G will handle 1/123456789 easily...but my 33S won't. :) Best regards, Hal

            
Re: Fraction writing in RPN
Message #7 Posted by James M. Prange (Michigan) on 20 Nov 2006, 4:53 a.m.,
in response to message #6 by Hal Bitton

Actually, regarding fractions, the 49 series has additional functionality compared with the 48 series.

The 49 series adds the "exact integer" (object type 28); the only limit on the length of an exact integer is available memory. When in "exact" mode (flag -105 clear), numbers entered without fraction marks are compiled to exact integers. With flag -3 cleared ((Function -> symb) and flag -2 cleared (Constant -> symb), a calculation won't change the exact integers to "real numbers" (object type 0) unless a real number (or an expression which contains a real number) is an argument. Additionally, there's a "textbook" display mode, which displays an expression on the stack in a manner similar to how it would look in the equation writer.

The PROPFRAC command, with an improper fraction (or expression that evaluates to an improper fraction) for its argument returns either an integer plus a proper fraction, or an integer. Alternatively, with an integer plus a fraction for its argument, PROPFRAC returns either an improper fraction or an integer. For example, '4/3' PROPFRAC returns '1+1/3', '6/3' PROPFRAC returns 2, '1+1/3' PROPFRAC returns '4/3', and '1+3/3' PROPFRAC returns 2.

For PROPFRAC, the CAS requires flags -2, -3, and -105 to be clear, which seems straight-forward enough, but also requires flag -17 to be set (radians mode), the reason for which being beyond me.

The ->NUM command will attempt to evaluate any object to a real number, erroring out if it can't.

I->R changes an exact integer to a real number, and R->I changes an integer-valued real number to an exact integer.

In case anyone is interested, the memory required for most exact integers is 5.5 bytes plus 0.5 bytes per digit (5 nibbles for the prologue address, plus 5 nibbles for the self-inclusive length field, plus 1 nibble per digit, plus 1 nibble for a sign field. The exact integer 0 is an exception, using only 5.5 bytes because it doesn't have a sign field. Also, some exact integers are built-in to ROM, in which case they need only 2.5 bytes (5 nibbles for the ROM address) in many cases. For example, the exact integers -9 through 9 will be compiled to this 2.5-byte ROM address form and the stack pointers will be the ROM addresses, but if one of these numbers is stored in a variable, the 5.5- or 6-byte object found at the ROM address is stored instead; 0 BYTES returns #0h and 2.5, but 0 'FOO' STO FOO BYTES returns #4789h and 5.5.

With an exact integer for its argument, the SIZE command returns the number of digits (as a real number) in the integer. An exception: with the exact integer 0 for an argument, SIZE returns 0.; bug?

Regards,
James

Edited: 20 Nov 2006, 6:00 a.m.

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