HP-27s and direct solutions legend
11-04-2018, 12:53 PM
Post: #1
 Vincent Weber Member Posts: 255 Joined: May 2015
HP-27s and direct solutions legend
Hi all,

Craig Finseth mentions in the solver section of his website that direct solutions (symbolic resolution) functions have been removed from the HP-27S, to save memory space.

This is obviously false: the HP-27s manual explicitly mentions direct solutions in details in two different sections. The HP 19B/27S technical manual also mentions this extensively, with no differentiation whatsoever between the two machines. And most importantly, trying exemples with direct solutions on the actual HP-27S works perfectly as advertised...

So, where does this legend come from ? Why is this still on Craig's site ?

Thanks and cheers,

Vincent
11-04-2018, 06:59 PM
Post: #2
 ijabbott Senior Member Posts: 1,114 Joined: Jul 2015
RE: HP-27s and direct solutions legend
Do you have a link / reference? I only see a mention that algebraic simplification was removed. Is that the same thing? http://www.finseth.com/hpdata/solvers.php

— Ian Abbott
11-04-2018, 07:45 PM (This post was last modified: 11-04-2018 07:48 PM by Vincent Weber.)
Post: #3
 Vincent Weber Member Posts: 255 Joined: May 2015
RE: HP-27s and direct solutions legend
Yes it is - symbolic functions based on the underneath RPL system to do simple variable isolation, provided the variable only appears once in the equation.
That's why X^2-4=0 cannot return -2 as a root, no matter what the initial guesses are, because the equation is directly solved to X=2. But if you write X^2-4+0*X=0, you fool the system into believing that the variable appears twice, hence forcing iterative solving - which can lead to -2 with proper initial guesses. I verified this on the real HP-27S, that's why I don't understand Craig's statement.
11-04-2018, 07:59 PM
Post: #4
 ijabbott Senior Member Posts: 1,114 Joined: Jul 2015
RE: HP-27s and direct solutions legend
Well, that's good to hear. I acquired one recently and love it!

— Ian Abbott
11-04-2018, 08:13 PM
Post: #5
 Vincent Weber Member Posts: 255 Joined: May 2015
RE: HP-27s and direct solutions legend
(11-04-2018 07:59 PM)ijabbott Wrote:  Well, that's good to hear. I acquired one recently and love it!
I's probably the most underrated calculator ever. It was sadly discontinued pretty early (< 1993). One could argue that the 19BII was a good replacement for it, with all its functions (except precedence and base conversions) and more... But the 27S (1) has a much smaller footprint (truly pocketable) and (2) has the scientific fucntions on keyboard, not burried in the MATH menu...

And its "programming" model is very unique. The flexibility of the solver allows you to do much of what keystroke programming can do, but in a much more user-friendly manner (you only write equations, not programs): you get conditionals (IF), loops (sigma) with the possibility of emulating undefinite loops, statements (L and G functions)... It is similar to Excel formulas in a way. If only it had the ability to define functions (to be reused) and to set values in list (for indirect addressing) it would be as powerful as a 42S, you could emulate matrices ! It does not have integration, but adding it as a solver formula is easy.

I guess it was too odd as a scientific calculator, and that the concept of a "do everything" (scientific + business) calculator never took off... A pity, because the 27S is really loved by those who know its outstanding capabilities.
11-04-2018, 09:02 PM
Post: #6
 rprosperi Super Moderator Posts: 5,254 Joined: Dec 2013
RE: HP-27s and direct solutions legend
(11-04-2018 08:13 PM)Vincent Weber Wrote:  The 27S is probably the most underrated calculator ever. It was sadly discontinued pretty early (< 1993). One could argue that the 19BII was a good replacement for it, with all its functions (except precedence and base conversions) and more... But the 27S (1) has a much smaller footprint (truly pocketable) and (2) has the scientific fucntions on keyboard, not burried in the MATH menu...

And its "programming" model is very unique. The flexibility of the solver allows you to do much of what keystroke programming can do, but in a much more user-friendly manner (you only write equations, not programs): you get conditionals (IF), loops (sigma) with the possibility of emulating undefinite loops, statements (L and G functions)... It is similar to Excel formulas in a way. If only it had the ability to define functions (to be reused) and to set values in list (for indirect addressing) it would be as powerful as a 42S, you could emulate matrices ! It does not have integration, but adding it as a solver formula is easy.

I guess it was too odd as a scientific calculator, and that the concept of a "do everything" (scientific + business) calculator never took off... A pity, because the 27S is really loved by those who know its outstanding capabilities.

I totally agree, the 27S is a great machine, and is the only Algebraic HP machine I will use. If only HP had released the 27SII with RPN (like the 17BII and 19BII), it would have gone on to huge success and very widespread use, but HP probably feared it would seriously impact sales of the 48SX, introduced around the same time-frame. And that likely was correct reasoning; I think a lot of folks would have stayed with RPN.

--Bob Prosperi
11-04-2018, 11:49 PM
Post: #7
 Benoit Maag Member Posts: 77 Joined: Jan 2014
RE: HP-27s and direct solutions legend
Same here - I love my HP-27s and agree it is so underrated
Clean and solid design, so easily customizable with the solver, great display...
Maybe Swissmicros could make a DM27 ?
11-05-2018, 12:06 PM
Post: #8
 Vincent Weber Member Posts: 255 Joined: May 2015
RE: HP-27s and direct solutions legend
(11-04-2018 11:49 PM)Benoit Maag Wrote:  Same here - I love my HP-27s and agree it is so underrated
Clean and solid design, so easily customizable with the solver, great display...
Maybe Swissmicros could make a DM27 ?
I don't think so. Unless Thomas Okken first makes a free27, which I doubt he will make. The HP-27S ROM, like all pioneers, remains copyrighted by HP, which prevents to distribute an emulator with the ROM...
11-05-2018, 02:07 PM
Post: #9
 Dave Britten Senior Member Posts: 2,074 Joined: Dec 2013
RE: HP-27s and direct solutions legend
I also often sing the praises of the 27S. I really wish HP had made a 27SII with RPN. The solver is really powerful, and it'll even do symbolic solutions using functions like HR() and HMS(), so you can enter an equation like "HR(T2)-HR(T1)=HR(TD)" for calculating the difference between two times in H.MMSS format, or calculating a time +/- some span of time. I've also got mine stuffed full of a bunch of different probability distributions and formulas, and the SPFV/SPPV/USFV/USPV functions make it easy to do highly accurate and sophisticated financial calculations.

I'd love to see Free42 forked into Free47, maintaining all the existing 42S features, but also including those that are specific to the 27S, like the financial functions, list editor (which makes a great, if simplistic account register), and symbolic solver. For now, I've implemented most of the financial features as keystroke programs, and the DM42 is fast enough that solving RPN programs is plenty quick compared to the HP symbolic solver (though it's still often easier to enter and read a quick symbolic formula compared to a keystroke program).
11-06-2018, 05:01 PM
Post: #10
 Jlouis Senior Member Posts: 705 Joined: Nov 2014
RE: HP-27s and direct solutions legend
(11-05-2018 12:06 PM)Vincent Weber Wrote:
(11-04-2018 11:49 PM)Benoit Maag Wrote:  Same here - I love my HP-27s and agree it is so underrated
Clean and solid design, so easily customizable with the solver, great display...
Maybe Swissmicros could make a DM27 ?
I don't think so. Unless Thomas Okken first makes a free27, which I doubt he will make. The HP-27S ROM, like all pioneers, remains copyrighted by HP, which prevents to distribute an emulator with the ROM...

But the 12c, 15c are copyrighted as well and was cloned by swissmicros. The sales number of swissmicros don't bother HP.
11-06-2018, 05:17 PM
Post: #11
 Vincent Weber Member Posts: 255 Joined: May 2015
RE: HP-27s and direct solutions legend
(11-06-2018 05:01 PM)Jlouis Wrote:
(11-05-2018 12:06 PM)Vincent Weber Wrote:  I don't think so. Unless Thomas Okken first makes a free27, which I doubt he will make. The HP-27S ROM, like all pioneers, remains copyrighted by HP, which prevents to distribute an emulator with the ROM...

But the 12c, 15c are copyrighted as well and was cloned by swissmicros. The sales number of swissmicros don't bother HP.
The Voyager case is slightly more complex. The ROMs don't hold a copyright. However, since HP is still selling the 12C, and used to sell the 15C limited edition no so long ago, and also sells 12C/15C iOS/Android Apps, HP is pressuring Google and Apple... Go12c was removed from market, as well as other emulators, even though it did not come with the ROM ! Nonpareil does not offer the Voyagers anymore.
I believe there is no legal ground for this, but it is not easy to go against Google.
The fact that SwissMacro is not on HP's radar does not mean that this will last forever...
11-07-2018, 11:25 AM
Post: #12
 Thomas Okken Senior Member Posts: 1,765 Joined: Feb 2014
RE: HP-27s and direct solutions legend
(11-06-2018 05:17 PM)Vincent Weber Wrote:  However, since HP is still selling the 12C, and used to sell the 15C limited edition no so long ago, and also sells 12C/15C iOS/Android Apps, HP is pressuring Google and Apple... Go12c was removed from market, as well as other emulators, even though it did not come with the ROM ! Nonpareil does not offer the Voyagers anymore.

And yet, there are 12C and 15C clones, by "Vicinno Soft LLC," in the iOS App Store. The 15C emulator has been around since before HP released their own 12C and 15C apps (the 12C clone came later). Judging by their change histories, they were probably pressured to remove the HP logo from their icons and skins, and to remove the acronym "HP" from their app names. The apps themselves appear to be emulators, not simulators, although I'm unwilling to spend \$6 each to get them and make sure.
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