|Re: HP 20S - manual question|
Message #7 Posted by Karl Schneider on 6 Apr 2006, 3:15 a.m.,
in response to message #6 by Thomas Radtke
Thomas R. posted,
More difficult: To understand what the functions do and how to prepare the input (or read the output), you need the manual;(.
That, really, is my main gripe about the HP-20S and HP-21S -- the loadable keystroke programs for useful functionality that I'm sure was touted on the package. It's a case of marketing prevailing over good design.
As Tom pointed out, the HP-20S loadable functions -- such as "root", "int" and "3 by 3" -- are not very intuitive, which is an attribute of the built-in SOLVE and INTEG functions and matrix operations on the HP-15C released six years prior. One must repeatedly consult the HP-20S manual, which may even be forbidden as unauthorized printed material in a test setting.
But there's a more fundamental problem with "root" and "int": When the functions are loaded, the previous contents of program memory are cleared! Now, these loadable functions require a user-defined program to execute. Let's say that the user has programmed a mathematical function, evalulates it at a few points, then wants to solve or integrate it. Load "root" or "int", and poof! goes the user's program. Not very smart, huh?
Contrast that with the HP-15C, where all of its functionality is complementary.