On Jul 14, 2006, at 17:51 UTC, Bob Delaney wrote: > CalcPad's ability to define and initialize variables is really neat! > And its ability to handle units is useful for physics students.
Thanks. It's also handy for physics dabblers such as myself (I often spend my evenings calculating moments of inertia for space habitats.) Tracking units in a calculation catches many types of common errors (such as multiplying when you should have divided, or shifting the decimal improperly when combining different measures). > If I go back up and redefine x0 as 3 m, the position > expression >automatically< changes to 89.4 m. Really nice! Thanks -- that's the power of the worksheet metaphor over a standard calculator. (Not my innovation, BTW; inspiration came from Mathematica, MathCAD, and MathPad.) > I did have a problem when I tried to use mixed units... > Neither ft or feet would work. This did: > > x0=3 foot: 0.9144 m Yes, that's because (as you surmised) "ft" and "feet" are not a defined unit (see "Built-In Units" under the Help menu for the full list). All units were defined in the singular, and Imperial lengths were spelled out: unit inch = 2.54 cm unit foot = 12 inch unit mile = 5280 foot This was partly driven by the fact that I couldn't use "in" for inches, since "in" is a keyword in CalcPad. So if that's inch, then it made sense to define the others as foot and mile. However, I do see that one might be tempted to use the common abbreviations or plural forms. Maybe I should define ft, feet, inches, and miles. Maybe minutes and days too? Metric units mostly don't suffer from this confusion -- the abbreviations are standard and universal (with a few exceptions, like the use of "gm" for gram). But with Imperial units, maybe it'd be better to have multiple ways to say the same thing. > I'm sure you've given the ability to extend recognition to ft and > feet, but common units like these should be predefined. But that's a > very small criticism of such an excellent calculator. Thanks very much for your feedback. You've also made me realize that my "Built-In Units" help page does not describe the *really* built-in ones, i.e., the eight fundamental units. I'll add that too. Best, - Joe -- Joe Strout -- [EMAIL PROTECTED] Verified Express, LLC "Making the Internet a Better Place" http://www.verex.com/ _______________________________________________ Unsubscribe or switch delivery mode: <http://www.realsoftware.com/support/listmanager/> Search the archives of this list here: <http://support.realsoftware.com/listarchives/lists.html>
