calculators mathematics

HP 35s Calculator Annoyances III

I keep saying how much of a fan I am of the RPN mode, and have used it on and off since high school. But times have changed, and HP needs to find a way to manipluate the logic of repeated calculations to make RPN still come out on top, but I feel discouraged, and feel there is no turning back.

I’ll tell you why. For one thing, you can’t enter any calculation in a mode involving stacks and operators, which is at the heart of RPN logic, and expect it to repeat without some way of remembering each operator and number you pressed. And the only way to do that is to really learn how to program this calculator, then preferably bind the program to a key. So, this is really not a calculator for sissies. At least, not unless you stay in algebra mode.

There was one more thing that I don’t think I’ve mentioned: viewing numbers in scientific notation sometimes requires you to use the scroll feature. This is because it will show you as many as 12 digits, pushing the power of 10 exponent off the immediate display.You need the left arrow to see what you missed.

calculators mathematics

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.