Plus42 Equations, Preview Release

[Thomas Okken]

(12-13-2021 10:36 AM)Nigel (UK) Wrote:  Another point: I've noticed that (for example) dividing 1_yd by 1_ft gives 1_yd/ft, rather than 3. (Adding zero to this does give 3.) Is this deliberate?

Yes, while multiplying and dividing, it doesn't do anything to simplify units, beyond making sure that no unit appears more than once. So it will collect ft*ft and turn it into ft^2, and ft/ft will cancel out, but there is no awareness that yd/ft = 3 at that point. It won't even recognize that m/cm = 100.

Adding zero happens to work in this case, but that's more of a side effect than a feature: when adding, the contents of Y are converted to match the units of X, and it is this conversion that causes the units to be simplified. If you were to do, say, 1_yd/ft ENTER +, you'd get 2_yd/ft.

This behavior is copied from the 48G, I figured it was OK because it's familiar, and because you can always simplify the units using UBASE or UFACT (or by adding 0, if you happen to know the real value is dimensionless).

(12-13-2021 10:36 AM)Nigel (UK) Wrote:  

(12-10-2021 09:15 PM)Thomas Okken Wrote:  2. Since there's only one shift key, LeftShift+Unit is not available as a shortcut to convert to a unit, you have to use CONVERT, or attach the desired unit to zero and add that to the number you want to convert. (That second trick doesn't work for converting to and from Celsius or Fahrenheit, though.) I'm still thinking about a less clumsy way to handle CONVERT.

How about using the decimal point as a left-shift key for CONVERT? If 14mm is in the display, then pressing "." "yd" would convert to yards without the need to press "+". Perhaps this could be made to carry out temperature conversions automatically as well?

I'm leaning towards a somewhat unorthodox UI: keep the unshifted unit the same, as it is now, but for shift+unit, pop up a menu, with choices "divide by," "convert to," "factor," and "cancel." It's a bit ugly, but it does have the advantage of making all the important functionality available with just one additional keystroke, and making it all really easy to find.

I haven't actually decided on that route, though. I am open to other suggestions...