HP50g : Symbolic solver oddities or user errors?

[Vtile]

Hello,

I'm relatively new for HP calculators, I have had a year now this HP50g and I have formed so deep hate & love relationship to it. Upgrated from TI-83+ to finally have a calc that have strong CAS, integral transformations, complex numbers and solver (I blame Matlab and Maple) to make my life easier .. yeah sure .. when now reseated myself in the school bench again with some odd years without higher math involved

Recent problem is the symbolic solver, it is pretty counter intuitive to use with all the needed flag settings etc.

First problem I had a while ago were now forgotten function in form more or less a simplistic a^(x^-1)=b giving some odd error. The solution for that were that the equation needed to be evaluated first with the eval command in approx turned off in CAS submenu in MODE. Simple solution were to make a small userPRL program to handle these tasks. Anyways something pretty basic logarithmic with evill decimal numbers that other calcs were eating without any hickups

Yesterday while doing another UserRPL program for totally different task I managed to make something wrong and the 50g tilted and asked if I want to "try to save the memory" or something similar, after that the solver had gone haywire ie. it didn't give a solutions just a empty curly pracess {}. A two hours ago today I made a reset button reset, F1+F6+ON reset and taking all five batteries out and leaving it sitting for a while, it seems it did reset finally.

Now the simple equations work, but when I did throw some random stuff I found out it does not solve them in fully ie. for random equation (x^3)*1=(x-2)/(2+x^2) it only solves the real solution, even if the calculator is in complex mode. In fact there is text "Unable to factor" popping in the top part of the screen for a split of the second. My CASIO-classpad2 (which were totally wrong purchase) gives the imaginary solutions without hickups while complex mode is turned on and so does the wolfram alpha it seems.
http://www.wolframalpha.com/input/?i=%28...2%2Bx^2%29

What is wrong with the HP50g and what all flags should be turned in which way to give the solver as much power to make symbolic calculuss as possible? Any ideas current situation is really pita since I lost confidence to my HP50g until I sort this out.

PS. The "Registration question" for this page 500 30 + ... do not work in my hp50g assuming "roll down" is down arrow in RPN mode.

PPS. I'm using SOLVE -command in RPN mode, it seems it doesn't matter which way I access to it (S.Solver menu or UserRPL.

[Han]

Can you share exactly what you typed (so that we may copy your input into the HP50G emulator and see for ourselves the issue you have been having)?

[Vtile]

MMmm.. I so much would love to throw this to trash bin atm..

I'll try to gather some examples with more specific information next few days, now I'm too p**ed off to think clear.

[Vtile]

Ok, well I pulled my notes out, it were even more simplistic I did remember. The first problem I encountered with the HP50g CAS were a equation: 1389=1.5*500*X^0.6 where 1.5 is a variable, but this time given as a number. So nothing too complex.
Solution would be something like X=(1380/(1.5*500))^(10/6)

So I did want a "non aproximated" answer for later use so I turned the approx mode off also the flag 123 - Forb. Swirch Mode is true in setting behing MODE key to not allow aproximation turned on while using solve. Now..

I prefer the equation editor for entering these so keystrokes would be:
1390 r.shift = 1 . 5 * 500 * X y^x 0 . 6 ENTER (to enter the equation to stack and exit from EQW.
In stack view:
X ENTER L.shift S.SLV 6 OK (no soft menu enabled atm. so it is pop-up menu)
"Solve ERROR: Non unary operator" <- Seriously wtf???

If aprox mode is on the answer would be e^(1.67*LN(1.852)) <- non interested about

... Now this is getting interesting, I can not replicate above anymore. The flag 123 seems not to stay up and the SOLVE command asks every time if I want to turn aprox mode ON yes/no, if no it just gives "SOLVE Error: Mode switch cancelled" .. Pulling my hair off atm...

Resetting with F1+F6+ON doesn't allow me to answer NO to question "Try to Recover Memory" what the hell is going on with this pile of silicon chips.

How I can make a full force reset that resets all and everything to factory defaults, microwave oven??

..I'm so sos os so .......

PS. Heh. Command VER gives information:
"HP49 CAS by Parisse, Heiskanen & Fiechter
4.20060919"
I though I purchased 50g not 49 .. Is the CAS version up to date or are this Chinese pirate copy (wouldn't not be too suprised if such would exist) it also number "HPK-49GPLUS(B)" at the back oh the calc while above the display it says what it should 50g..

PPS. Seriously, this unit have made some odd thing along this year I have had it. At times it do not take key presses at once and then when pressing again it doubles the press, once the keyboard test behind "F1+F6+On" menu the keyboard didn't take Up-arrow, but after reboot anything were fine again, now this thing with CAS. Unfortunately HPs are rare like hen's teeth here these days (assuming it is because of super restrictive and conservative high school exam rules and TI&Casio are stronger at that stage what to offer and later just phone/laptop) so I can not have other unit just to check if mine is foulty. :/

[Han]

The HP50G has some buggy behavior with solve if the flags aren't just right.

Your formula is in "non-exact" form because of the decimal representation of 1.5 and 0.6. Use the XQ command to convert an object to exact form. Then you can solve for the answer exactly (which appears to be your goal).

[Vtile]

(10-29-2015 07:17 PM)Han Wrote:  The HP50G has some buggy behavior with solve if the flags aren't just right.

Your formula is in "non-exact" form because of the decimal representation of 1.5 and 0.6. Use the XQ command to convert an object to exact form. Then you can solve for the answer exactly (which appears to be your goal).

Thank you Han for that golden tip, XQ command solved that problem (wondering which is the reason the SOLVE command isn't using it while the calc is in NON approx mode). I must update that XQ to my solve routine with flag sets etc. when I need/want exact solutions.

My "eval before solve in nonaprox mode" aproach did give some good results, but after yesterdays system crash and reset it at my opinion not work anymore as it used to (I'm not using the solver daily so I didn't keep attention and I'm constantly jumping complex to real to polar to rectang., aprox to "numerical", Pi as symtol to numerical.. etc. Can not keep the track all the settings.), must be some really odd flag setting somewhere that were turned on by me or the programs along the year or something.

Is there somewhere a somekind of list of known "oddities"/pitfalls and flag settings of 50g CAS and solve? That I kind of were asking also in the first post.

Just for interest how Primes CAS, "textbook mode" and solve (and comparable CAS related commands) compare to HP50g?? I'm not / were not too keen other features of it ie. color display (why not epaper), low battery time, Li-ion non-standard? accumulator, basic style programming mnemonic (pita to type with calc, especially since none of the facturers are using the cellphone style of typing with 9 keys), lack of RPN in every folder/mode, lack of through illuminated keyboard, lack of separe qwerty keys to cope the basic programming, heavily mapped/foldered/ OS or UI (home, CAS, etc. etc.). ... seriously why there is no graphic, cas, low energy, illuminated on/off, engineering/sci/pro programmable (with something efficient like UserRPL [for quick and dirty] & SystemRPL combination) calculator with good keyboard and dimensions rougly 6½x12 centimeters (can be used with one hand and fits to pocket / slim briefcase) on the market.

Edit. Aprox to nonaprox.. lost in translation sry.

[Vtile]

Another interesting "feature" of the HP50g CAS I just found out when eyeballing my old math book with 50g on the another hand. If we enter an equation of (1+j)z = 2 - j and then solve the X when the comp..calculator is on exact mode, rectangular coordinates, complex on, radians on, flag 27 set ('X+*Yi'->'X+*Yi').

When solving (SOLVE) the X from simple complex equation (1 + j)*z = 2 - j
calculator gives out: X=(1-3j)/2, this is right solution, but wrong representation as it should be 'X+*Yi' or in this case 'X/a+*(Y/a)i' as set on the calculators settings.

Now if I take a numerical solution of X (->num) it turns out a mathematically right solution in totally wrong form as it gives
(0.5,-1.5) which is not a 'X+*Yi'.

Much confusing and trust eating that the calc doesn't seems to give a damn about settings (a flags) I order it to follow.

[Bill Platt]

Quote: seriously why there is no graphic, cas, low energy, illuminated on/off, engineering/sci/pro programmable (with something efficient like UserRPL [for quick and dirty] & SystemRPL combination) calculator with good keyboard and dimensions rougly 6½x12 centimeters (can be used with one hand and fits to pocket / slim briefcase) on the market.

Wellllll....let's just say that it is something of a miracle that there are still "6x12" centimeter machines that have any design function for this, *at all.* I think you pretty much answered the question already: Wolfram, MAPLE etc...

[Vtile]

It is also miracle that books made from paper are still around. Did you know btw. that there is some small manufacturers that have reintroduced cellphones without anything else than just call and text messages?

Using mathematical scientific software is overkill for many tasks and for sketching the pen and paper (digital or traditional) is still pretty awesome tool where you are not pound by capabilities of "on the self software".

Quote:Based on marketing studies done at the time, the HP-9100 was the "right" size and price for a scientific calculator. The studies showed little or no interest in a pocket device.

Smart phone with "calculator simulator" is close, but the software keyboard is typically non-optimal to use since it doesn't have feedback or it is too general (plus all issues with dry,wet etc finger tips). Also the keys per cm² is pretty low compared what can be done with physical devices where is 3rd dimension in use. Those are also relatively slow to use even for the people of age 20..24 who are pretty much lived with devices like those whole their life. Also there comes all the issues related to the "jack of all trades master of none" with phone apps. Then there is two task, but one device problem, what is typically seen in "paperless" offices without a though given for resources where you should read eDocument for information and should fill the information to another document based on information ascuired from another, but you have only one monitor. Ending up "channel jumping" between softwares and cursing your organisations resource planning.
Then there comes the strickt phone restrictions on some places and IT software voids ruled from somewhere in ivory tower for next 5 years.

What comes to laptops they are nice and are pretty much in hand every where, but they are purposefully made for typing words, not mathematical stuff. Their UI for mathematics (keyboard) is nonexistent and they do not fit to the pocket of my jeans.

Also with calculator one can not access to the eJunkies paradise called internet.

There should be no demand for ie. HP12c, nor any other small palm sized calculator at all.

PS. Ie, HP35S is not a palm sized calculator nor it is not pocket sized calculator, it is more a table top calculator in size as is all the CAS and graphing calculators I'm aware of.
PPS. Basicly a HP42S brought to todays computing power (shrinked down 48 family) (with battery life over speed), a tad smaller so you actually can use it with one hand, since 8cm is just hair over wide. Would buy 42S without heart beat if they wouldn't be so damn expensive in mystery 2nd hand condition.

[Bill Platt]

It is somewhat dejavu for me, this question of yours. We went rather exhaustively through these discusssions, right here, back in the beginning of the 21st century. Back then the new device for putting emulators to work was the Palm. How things change.

I will note that my professional use of calculators has fallen steadily over the past 15 years. Ironically in the years when I depended on one, I had only one (11c) and now that I really don't need one at all, I have over 20 of them...and they sit in a box most of the time.

The 48G series in the collection still sees use though. Mostly for the mere fact that it is fantastic for number doodling with that long stack. The 15c and 20s get lots of use too. My 27s is my all time favorite. But, lately I've left it idle too much.

Some of this is just how work is going. Only 5 years ago 27S got lots of use. Flying half way around the world repeatedly, doing engineering, the calculators and a pad of paper were great. The laptops would die too fast and it is too cramped.

In the office, the tools at your fingertips on the confuser are just too good now.

[Vtile]

(11-09-2015 12:40 AM)Bill Platt Wrote:  It is somewhat dejavu for me, this question of yours. We went rather exhaustively through these discusssions, right here, back in the beginning of the 21st century. Back then the new device for putting emulators to work was the Palm. How things change.

I thought it were the 49 which were emulating a Saturn ( I can remember a mate had a Sega Saturn when I were a kid). There is still a Radio around, while TV were killing it for a fact. So are the LP records and Longines mechanical wrist watches.

(11-09-2015 12:40 AM)Bill Platt Wrote:  I will note that my professional use of calculators has fallen steadily over the past 15 years. Ironically in the years when I depended on one, I had only one (11c) and now that I really don't need one at all, I have over 20 of them...and they sit in a box most of the time.

The 48G series in the collection still sees use though. Mostly for the mere fact that it is fantastic for number doodling with that long stack. The 15c and 20s get lots of use too. My 27s is my all time favorite. But, lately I've left it idle too much.

Some of this is just how work is going. Only 5 years ago 27S got lots of use. Flying half way around the world repeatedly, doing engineering, the calculators and a pad of paper were great. The laptops would die too fast and it is too cramped.

In the office, the tools at your fingertips on the confuser are just too good now.

It is changing not arguing that. What really grind my gears is that engineer at age of about 30 I can not have a decent modern professional engineering pocket calculator, nope (not even if I would be willing to pay for one since there is none!). The only ones are these brick sized battleship class calculators which were considered small when they were new in line "The RPL Family (1986)" I were on diapers back then ffs. My field is industrial automation and electrical (EE WIP) engineering and for those disiplines the HP50g fits the bill with lots of programmability and I know it can handle most if not any problem I can encounter when in field or in day to day when everything goes haywire, but it is so .. you know .. big. Like every other "modern CAS programmables" they are like https://www.youtube.com/watch?v=eQ_g_OI04pc the mighty 50 will end in a drawer or sitting on my desk, no way I will carry it around, it needs a briefcase its own. While it would be 100% doable to make it fit in my front pocket (button closed) with all of its functionalities (only with smaller keyboard and hair smaller display with 131x80 pixels), even with the ARM9 processor, I'm sure even more so if the OS would be blackboxed to run natively at ARM. But all that would be a miracle. HP is great It just had and still have that engineer weaponmaker status, for two reasons exceptional calculators and exceptional measuring devices. One is gone (keysight these days), will another survive the time, hopefully since if not there is just nothing worth to mention.

Even the "appstores" are not a new thing, that basicly existed in late 1970 era of HP calculators, based on the few words thrown out by the one designer of the Voyager series in that HP collectors event I come across in youtube.