HP48SX Lack of Laplace transforms


I am new to using symbolic type HPs. The old 48SX that I bought does not seem to be able to cope with simple Laplace transforms - it cannot fathom the necessary integration. I was surprised at this. I would be most grateful if someone could tell me if I am correct in my assumption that the HP48SX can't manage such an integration. Also, can anyone tell me if a card can be bought to enable the HP48SX to manage such transforms.

Thanks for your consideration of this problem.



Erable does Laplace and Inverse Laplace transforms and is available in an SX version... read the instructions carefully for special SX installation steps. I used it quite a lot in the old days.

Click here to download.

Scott Guth


If you want real symbolic power then get a 49 or 49+. Both have LaPlace/Inverse LaPlace commands. Both machines have a true CAS, quite good for a handheld, unlike your 48, which has sort of a joke CAS. Both machines can be bought cheaply, especially the original 49, going on eBay as new old-stock for $60-$100. The speed of the 49/49+ is much faster than the 48 as well. If your 48SX is in good shape it will sell on eBay to help finance your 49.

As for the Erable program for the 48, it was way overrated. I found it to be so full of bugs and limitations that it was not worth using. It was not until the author of Erable got paid by HP to develop the true CAS of the 49 that it become a good program.


Thanks I Claudius for your help. I was completely underwhelmed by my HP 48SX's symbolic abilities, but as a novice user I was wary of jumping to conclusions before seeking the opinion of more experienced users. So basically what you are saying is that the HP 48SX has a rubbish CAS. When I tried some Laplace transforms on an old TI-92 it performed well when given the transform as an explicit integration with lower and upper limits of A and B, then I could let A tend to zero and B tend to infinity.

It's a pitty that the HP 48SX could not provide a capable CAS, and it's only saving grace seems to be it's build quality - ah well.



Let's see, a graphic calculator designed with a custom 2 mhz processor complete with a high-level language somewhere around 1989 or 1990...

How about some perspective before you go criticizing a fifteen year old example of technology? Please don't forget the title of this forum - the HP Museum.

Do you call Wordstar a joke because it had no WYSIWYG print preview?

Edited: 2 Oct 2005, 9:51 a.m.


Hi Randy,

Good point...

I remember wordstar... (and DBASE II ;-)



To be quite frank, scrap or sell your 48SX. It's an underpowered dinosaur. I know this is heresy in an HP newsgroup, but I'll admit to owning a TI89, the handheld version of the old brick 92. The 92 has now been superseded by a somewhat smaller thing called the Voyage 200. The CAS in the 89, a version of Derive, is outstanding. If the 89 had an RPN OS and memory structure like the 49 it would be almost perfect. Indeed, if you're worried about build quality of the new 49+, and need a reliable calc with a good CAS, buy a TI89.

There are a number of very good programs available for the 89, an equation writer, and an nth-order difeqs program that also does LaPlace. You can find them and other links at



Thanks for the info, very interesting...



Most definitely, the CAS of the 49/49+, while far from perfect, is very good for a handheld. The Erable program for the 48 was quite popular, and the author was a Ph.D mathematician. HP did the smart thing in hiring him to write the 49 CAS. What killed the 49 was its bizarre departure from HP tradition, the ugly "frozen hamster butt" colored case, rubber keys, and stupidly redundant upper screen that scratched with air merely blowing across it. This is probably due to the 49 team being controlled by some very young just graduated engineers, a bad move. There is no doubt in my mind that if HP had simply updated the 48 with the CAS, Flash ROM capability and black screen it would have been a good seller. Then they would have lots of time to get the 49+ or the mythical HP50 right.

Now it's all outsourced to this Kinpo. HP needs to bring all calculator R&D and production back in house, and hire some first rate engineers and programers.

Edited: 3 Oct 2005, 8:50 a.m.


Hi, I Claudius,

So I gather from a casual read of these interesting threads, that the 48 is solid and nice, but sucks a bit computationally and the 49G has the firmware but is built like a kludge? Do I have that right?

I was thinking for tinkering round with some cheap graphing calc.
For under $100 U.S. what will I get on Ebay, do you think?




You could buy an Hp48Gii for under $100, new.
It is nearly the same as the Hp49G+.

But you could buy the Hp49G+ for $130 new from Hpcalc.org also. At a bit more than $30 over the cost of the Hp48Gii you get a much more capable calculator in terms of memory and upgradability. Today they are nearly equalivant, but as more software becomes available and the OS evolves the gap between the two can only widen.

If you abandon RPN, you widen up your selection significantly. But for brute force abilities, nothing else matches up to the Hp49G series aside from moving to a PC and math software (ie a PDA loaded up with software). However you give up a dedicated keyboard, fast boot up time, and the lowcost of a calculator in comparision.

The Ti-89 is a good second choice. But at $150, it is 50% more than your stated price ceiling.

Third in capability (CAS wise) is probably a tie between the Casio FX2.0 and an Hp40GS (available only in Europe). These calculators are a distant third in comparision to the Ti-89 above. I would say the Hp40GS should edge out the Casio, but it isn't yet formally available to confirm.

I personally still use an Hp48G at work. I use and carry a 49G+ for its wealth of features and its speed. But for general number crunching, I like my 48G better (I am slow to trust the keyboard of my 49G+ for desktop use).

If you shop ebay, you should get a 49G+ or an older Ti-89 for less than $100. But with the HP, you would not get your 1 year warrentee. I suspect it is worth the $30 more to have one year of support/trade in for the 49G+ and buy it new.


Actually, the first HP49 is the most reliable, whereas you're still taking a gamble with the 49+. The rubber keys take some getting used to, but they do work. There are quite a few new old-stock units available on eBay for $60-100. Get one of those and you won't have forked out megabucks. I have heard good things about newer serial numbered 49+s but not consistently. I'm going to wait a bit longer before trying another 49+. I went through several of the early ones, only to get one bad one after another. My original 49 works quite well. Aside from the case and keys, it is a reworked 48 with a CAS, big memory and file system.

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