Thursday, September 30, 2010

Save HP HP48G PLUS Graphic Calculator


As an engineer of 30+ years, and now an engineering professor, I truly believe the HP 48G series of calculators is one of the best calculators ever developed....even if it is not the most intuitive. I remember starting college with a TI calculator (an SR-50). At some point, someone turned me onto the HP calculators of the day. After using one for a short period, I knew this was the way calculators were suppose to work. Very fast, very logical, very easy to use!

The major reason most persons do not like the HP is due to the RPN (Reverse Polish Notation) logic and RPL (Reverse Polish Lisp) language employed by the HP; generally because they do not understand it. RPN logic is how math is done, even pencil on paper. It is extremely logical. Even algebraic entry calculators, when not set to textbook entry, employ RPN logic for functions (ie: logs, trig functions, etc.). RPN logic forces the user to start from inside and equation and work outward. Of course, this is exactly how one solves anything pencil on paper! As a simple example, the sum of 5 and 8 in algebraic logic AND in textbook entry is 5 + 5 = ??
In RPN, there is no equal key. Instead, there is an ENTER key. So one would press 5 [ENTER] 5 + To the unitiated, this appears confusing on the surface. However, when one understands how the mind processes information, and when one truly understands how mathematics is performed, one realizes this is exactly how one handles math without the calculator. This is why there are no parenthesis on an RPN calculator. They're unneccessary. The advantage of RPN logic becomes readily apparent when handling very long/complex algebraic expressions (ie: Bernoulli, Principal Stress Equations, Certain Thermodynamic Expressions, etc.).

Although I have no problem with algebraic entry logic, Textbook entry is something to be despised. I truly believe this entry method has done more to degrade the mathematical abilities of our students than anything else! Textbook entry is exactly what it sounds like. You enter the equation as it appears in the textbook, then press equals (or exc). Although this sounds like a good thing, I can tell you that the vast majority of mathematical errors made by my students are made due to the lack of understanding of basic mathematical heirarchy. This is lack of understanding is propogated by the textbook entry format. Even students who have calculators with algebraic logic generally make fewer mathematical errors than those using textbook entry! It is also an extremely slow method. When lecturing on a given topic, and solving long algebraic expressions, I (and students using HP's) solve problems far more quickly than those with algebraic and textbook entry calculators. This time factor is rather substantial. Generally, those with textbook entry calculators are left so far behind those using even algebraic only entry, they stop participating and allow others to perform the calculations!

I have three high-end Casio's, every TI from the 83 through th 89, and most HPs from the 25 through the 50. I own so many so I can help my students. I hate to say it, but I never have questions from students who own HP or Casio calcualtors, only those that own TI's. Never thought about that before now. I wonder why?

I have also done extensive programming with the TI's, somewhat less extensive with the HP's, and minimal programming with the Casio's. Most of my programming is for use with data loggers. The HP is somewhat more difficult to learn overall, but the learning curve is not that much greater than the TI or Casio. However, the HP pays dividends in the end, especially in terms of speed of calculation and in terms of available professional software. I have always thought the HP SOMEWHAT more powerful and with a much more close-knit support group than the TI, although I suppose that could be debated. The Casio is easily the most intuitive of the three and I believe far superior to the TI in most areas. Anecdotally, I've had a number of students go the Casio route when purchasing a new calculator and they've all preferred it over the TI. (did you know Casio is the calculator of choice outside of North America?) In my opinion, the TI falls in between the HP and Casio. All three are very fine calculators. All three will do the job. But the HP is unique in that it actually improves ones understanding of mathematical concepts and heirarchy to the RPN logic.

By the way, I have a number of friends who like the HP, but use the TI or the Casio. However, they seldom use it in textbook entry (they also deem it illogical). However, they usually use it becasue the department has selected TI's. This is especially true in K-12. But this is generally due to a difference in the business models of Texas Instruments vs. Hewlett Packard. Unfortunately, HP caters to the professional market, not the educational market.

In the end, the HP-48/49/50 series of calculators are GREAT calculators. I tend to prefer the high end 49/50's over the 48 series due to their use of SD cards, thus the ability to store high quantities of data. However, the 48G and 48G+ can still be found at a reasonable cost, thus comes highly recommended.Get more detail about HP HP48G PLUS Graphic Calculator.

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