42s questions and 42s vs 35s



#15

Had the 42s a week now, and enjoying it.

Questions
--------------
1. Cant seem to find a Normal distribution program for the 42s?
2. Once I get my head around it, will I be able to do the equivalent of the equation solver on the 35s on the 42s? I have to write an RPN program instead right? Is it fast?
3. Has anybody run out of ram?

42s vs 35s
-------------
1. The 42s manual doesn't seem as good as the 35s, not as many examples/programmes.
2. Has anybody run out of ram of the 42s?
3. Is the accuracy on solve and integration as good as 35s?
4. The keys on the 42s arnt light years better than the 35s, infact he sloped keys are nice.
5. The menu system and polish on the 42s is awesome


#16

Quote:
1. Cant seem to find a Normal distribution program for the 42s?

Try the software library on this site. Either the 41 or the rest, both have normal and inverse normal distributions. Conversion is straightforward.


Quote:
2. Once I get my head around it, will I be able to do the equivalent of the equation solver on the 35s on the 42s? I have to write an RPN program instead right? Is it fast?

Yes, yes and how fast? It is fast enough for most purposes. It is as fast as a modern fast CPU -- no.


Quote:
3. Has anybody run out of ram?

I haven't but I'm sure you could if you tried. 8kb is heaps for most purposes. If it isn't enough for you, search for the 32kb expansion and get your soldering iron out. You can also double the speed at the same time if you are keen.


Quote:
1. The 42s manual doesn't seem as good as the 35s, not as many examples/programmes.

I'd have said it was far and away better. It covers everything, the printed manual I got with my 35s was very very thin in comparison. Do they even ship the printed manual anymore.


Quote:
3. Is the accuracy on solve and integration as good as 35s?

Yes, if not better -- I trust the results from the 42s, I don't for the 35s.


Quote:
5. The menu system and polish on the 42s is awesome

The menu system is the weak point in my opinion :-)
The polish is definitely there.


- Pauli


#17

When i said is it fast, I meant fast to type in compared to the equation editor.

Ps. Why does this forum software keep stripping out my carriage returns, my post is close to unreadable.

Daniel.


#18

Try putting [nl] at the end of the lines or wrap it up in [pre]...[/pre].

I enter equations faster as RPN than I do into an equation edition but that is a personal thing.

- Pauli

Edited: 18 Sept 2011, 7:46 a.m.

#19

Quote:
Quote:
5. The menu system and polish on the 42s is awesome

The menu system is the weak point in my opinion :-)
The polish is definitely there.


The HP-42S is slightly more usable than the HP-41 (as a calculator), IMHO. Not only because of its menu system, but also because there is only one shift key. I'd rather have more functions directly available from the keyboard, like in the HP-15C.

Wasicki :-)


#20

I never found the single shift a problem with the 41. Probably in part due to it's fully implemented user mode keyboard. The HP42S implementation is only partial (top row menu).

I don't mind menus too much as long as they are logical and relatively flat.

Cheers,

-Marwan

#21

Quote:
1. The 42s manual doesn't seem as good as the 35s, not as many examples/programmes.

HP provided "HP-42S Programming Examples and Techniques." This book is very useful.

#22

Please use the Enter key twice (!) to create a new paragraph. Or insert a "nl" tag in square brackets. Or, even better, use the tags for numbered lists, as stated in the advanced formatting section on this site.

Quote:
1. Cant seem to find a Normal distribution program for the 42s?

Programs for the Gaussian CDF and its inverse (quantile) are a very weak point in HP software. The one or other program even may be used as an example for errors and pitfalls that have to be avoided in numeric software. Most even resort to the good old Hastings approximation from the Fifties which is only good for three decimals.

Of course you can do both the CDF and the quantile using the 42s' Integrate and Solve, but there are far better options here. Some of them have been discussed for the 34s project.

What precision do you need? And what range of z resp. p has to be covered?

Quote:
2. Once I get my head around it, will I be able to do the equivalent of the equation solver on the 35s on the 42s?

Since there is no equation mode on the 42s you will have to use RPN. While speed may be comparable in general terms, there is something the 42s cannot do: solving your equation symbolically. The 35s (in most cases) can do that if (!) the variable to solve for appears only once. A very simple example for the Pythagorean theorem on the 35s:
  [EQN]
A^2 + B^2 = C^2
You now can solve for any variable and the 35s will return the result immediately. No inital guesses required, no iteration, no nothing. Press SOLVE A. You are prompted for B and C, and the value for A is returned within a fraction of a second. In fact, the 35s rearranges the equation and evaluates A as the square root of C^2 - B^2.

Or, try the example in the 15C manual, a stone dropped from the Eiffel tower: h = g/2 t2

  [EQN]
H = g / 2 * T^2
Yes, the 35s also knows the value for g. ;-)

Solve T, enter H and get the result instantly. Replace the constant g by a variable G and you can also solve for that. I really like that. ;-)
Quote:
Is the accuracy on solve and integration as good as 35s

I assume both use the same or at least very similar algorithms, so there should not be much difference. The nice thing on the 35s however is that you can also solve and integrate equations.

There may be a difference if the 35s uses the mentioned feature and solves an equation symbolically. Consider X^2 =  8. The iterative approach on the 42s should return two adjacent results 2,82842712475 and ...474 (the exact value is somewhere in between), while the 35s evaluates X = SQRT(8) and returs only that result (...475).

This example also shows that you will always get one single result, so in this case the negative root will not be returned. In theses cases it's easy to force an iterative calculation: simply add 0*X to the equation so that X appears twice. ;-)

Quote:
The menu system and polish on the 42s is awesome

There are several things on the 42s that are awesome. ;-) However, it does not offer any kind of mass storage or communication with something other than a printer. A 42s with a 41C-style keyboard (and alpha entry) with a simple SD(HC/XC) slot - that would be something that made (not only) my dreams come true.

Dieter


#23

Well, The 35s came with a program in the manual, and its as accurate as my tables book. I dont want to have to put in Z-scores, i can just put in mean and sd (once) and then find the upper tail or inverse. Real easy.


Ive got all the 42s manuals from the DVD set from this site. Theyre ok, but have less programs in them.


Matrices is very nice on the 42s, but te equation editor on the 35s is good for quickly putting in a solution or Euler for an ODE. Im wondering if I persevere with RPN I can be fast enough to code in exams.


The most amazing thing about the 42s in comparison is the catalog for programs.


Daniel.


#24

Quote:
The most amazing thing about the 42s in comparison is the catalog for programs.


The 35s has some program catalog function as well:

Left Shift - MEM - 2PGM

With the up and down arrow keys you can browse the available program labels, not too much different from the 42s.


#25

Quote:
not too much different from the 42s

Except for the possible length of the program names.
#26

snaggs, if you're going back for a degree in applied math(s) you might consider adding an HP 50g to your toolbox. There's vast numbers of programs available and with the cable/SD card options it's easy to add programs to the libraries.

Regards,

John


#27

I had a 49g, which I dont like the look off. So I've bought three calculators in the past 2 months and are trying to decide between them;



35s : Great programs available, easy to find things (printed on buttons), no matrices!!!

42s : No fractions, which is annoying when working with Matrices with fractions in them!

48g+ : Read the manual, forget stuff, still have no idea how to do stuff on it and get lost. I got as far as the teach command, tried to store something in N, but its not lower case N so the fibon program error, and now the "left shift" Clear shows me no options and I can't delete variable "N". Press "on" button as many times as you like, and it doesnt let you run away and go back to home. 20 minutes has ellapsed and I've worked out that I created a program and deleted it. Maybe I just need to spend more time. Still can't run the FIBON example, it just beeps at me with "undefined name". Its not very encouraging!

Quote:
snaggs, if you're going back for a degree in applied math(s) you might consider adding an HP 50g to your toolbox. There's vast numbers of programs available and with the cable/SD card options it's easy to add programs to the libraries.

Regards,

John


Edited: 19 Sept 2011, 2:33 a.m.


#28

Tried typing '3/2' into a cell and it came up with an error. Is this illegal?

Daniel.


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