Tag: Stack

HP Calculator Annoyances II

I am as much of a fan of the RPN mode as anyone. But the implementation of RPN in the HP calculators have to keep up with new developments in technology.

For one thing, I had trouble in RPN mode, to make a list of random numbers. Suppose you wanted to make a list of numbers with a certain variability such as:

150 + 25*RAND

I would do this to generate a list of random numbers with a minimum of 150, and a maximum of 175. RAND is the random function which generates a number between 0 and 1. In RPN, I would need to enter 150 and 25 in a stack, then my RAND, then * and then +.  That generates one such random number. To generate more numbers, such as a list of 25 numbers, you need to go through the whole thing again, 24 more times. It may have been necessary 20 years ago to actually repeat the same keypresses over and over like this, but dual displays have been around for slightly longer than 20 years, making these operations a lot less error prone, and way more efficient.

You may do this calculation better in algebra mode, using the left arrow key to go back to the statement you typed in, then press ENTER to get the new number. This will cause fans of RPN to vascillate back and forth between algebra and RPN modes whenever they need to take advantage of certain features. It is likely that the official HP claim that RPN is more efficient with respect to key presses is becoming less and less true as technology improves, unless HP can figure out how to repeat a stack of numbers and operators.

More on this next Wednesday.

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What is old is new: RPN on the HP 35s Scientific Calculator part 3

The print-edition of the HP 35s manual

For those of you lucky enough to purchase the calculator back in 2007, you more than likely had the full 200-page print edition of the user manual. HP discontinued the print edition, possibly later that same year. It has been replaced by a smaller 40-page mini manual whose only real useful purpose has been to help me review the main points of RPN. If you are a beginner, then you need to access the full manual which is now stored on CD. My CD, which I bought less than a week ago, appears to have been last updated in 2009. The same CD also has the same manual in 15 other languages.

You would have had the ability to review the book at your leisure, rather than on a laptop screen the way I have to view it. It is a bit of a deterrent and is tiring on my eyes, but I guess it beats having no book. I have discovered that you can purchase copies on E-Bay if you feel desparate enough for a print copy. You will probably shuck out your dollars for a print copy if you want to program, or if you want to have a more through mastery of its system of menus.

However, if you program, it must be stated quickly that much of the programming language is printed on the keyboard above the keys, and are active in program mode. It is definitely a caclulator that had its keyboard laid out with the programmer in mind, and with their needs as the higher priority. A look at the keypad shows a lot of programming commands rather than statistics, summations, or clearing the stack, all of which require menus. The “STO” function requires the blue shift key to be pressed first; and the functions for x2, log, ln all require a shift key to be pressed first. For whatever reason that perplexes me, there seemed to be a need to cram a good fraction of the interface of the calculator with various conversions: metric to imperial, fraction to floating point, degrees to radians, signed to absolute value. It takes up 10 of the 43 keys. Since none but grade-school calculators have these conversions, I am not sure of the motive. It is likely that it helps in the programming to save coding effort.

It seems to be all about the programming. Programming takes up 5 chapters or 100 pages of the 382-page booklet. Plenty to learn for the HP 35s programming enthusiast.

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