How much has RPN/RPL spoiled you?

[Dave Britten]

(06-04-2015 03:54 PM)Tugdual Wrote:  I personally tend to avoid complex programs on calculators, for the reason that keyboard is not sized for this activity; so RPL seems the perfect answer to me. Now to your point, you often need multiple programs to achieve one task for the reason you mentioned which again shows that the calculator is not the right tool for bigger applications.

A complex program doesn't necessarily have to have a complex user interface, though.

The ETA program I'm finishing up displays a menu bar when you run it. Just hit F1 ("Log") and enter the current value to log it to the data lists, along with the current timestamp (retrieved automatically from the RTC). If you have enough data points, it then runs the regression automatically, and displays the completion estimate and correlation. Then you can use the "Plot" menu item to draw the graph. There's also a "Setup" option where you can enter the target value, select a regression model, and choose how many of the most recent data points to look at when estimating (or 0 to use all of them).

It's a relatively large program for a calculator, but the user interface has been kept simple and similar to the other built-in apps. I've written a similar program on my 48SX. It's much more basic overall - it simply expects you to store a value in TARG, then enter a data value on the stack and run ETA to log a data point. Then it runs the recalculation routine, and there's another program that will draw a plot if you want. Just with those features, the code is still a lot uglier and unpleasant to maintain.

The RPN programming paradigm tends to shine more with the kind of stuff you'd do on a 42S/41C/32S/etc. The TI-89 is a lot clumsier for interactive use due to the symbolic command entry, but programming larger applications is much more straight-forward.