Start the app. Your iThing becomes a calculator, and you can refer to the screen as you read this description. (Tap MAIN for the app, then WEB to get back here to read the next step.)
The number-cells—one white, five light green—are called "fCells". At the moment they are the integer, numerator, and denominator parts of two fractions. At startup, both fractions are blank (all parts are 0). The numerator of F1 is white because it is currently the active fCell. The little waving stroke /|/| is the digit cursor showing where the next input digit will go.
The role of the keystrip along the bottom is number entry. Tap the key for digit 1. Tap it again. See where the 1s went? See where the cursor is now?
The little circled x near the active cell is that particular cell's "clear button". Each fCell has its own. Tapping it clears that single cell to zero—try it.
At startup the cursor is always in the numerator of Fraction F1. A moment ago you cleared Fraction F1's numerator. Continue this first session by following the description below which—for the first four times you run Frrraction after each update—is duplicated in the narrow "InfoView" a.k.a. "PeekPane" at the left side of the screen.
Your Next Few Minutes with Frrraction
As just mentioned, at startup Frrraction's MAIN view shows two number-fields containing fCells F1n,F1d,F1i and F2n,F2d,F2i. Beside each fCell is an hCell ("helper" cell). Later you can change the contents of the hCells but initially most of them show the names of their adjacent fCells—and, after you've touched a few things on MAINview, H1d and H2d will do the same for their own f-companions.
Scroll down in the InfoView to read more and follow a startup example.
Each number-field is a fraction when, as you see at startup, all three of its Fcells contain integers (as noted by "All Integers" at the top of the screen):
integer plus numerator over denominator = Fi+Fn/Fd.
If decimals are present then up to three decimal-pairs are shown: F1n,F2n and F1d,F2d and F1i,F2i. (If either of a pair shows a decimal point then both members are decimals).
The member of a field-, fraction-, decimal-pair, or module with the waving cursor is the active member, the other member is its mate.
In all cases arithmetic combines active with mate and delivers the result to the active member. This holds true for fraction-arithmetic, decimal-arithmetic, and residue-arithmetic.
EXAMPLE:
Do this as you read it, either following along in the peekPane or tapping MAIN and WEB alternately.
Put 1 into F1n, 2 into F1d, 3 into F2n, 5 into F2d, then tap '+' to add; the result will be in F2; note the carry into F2i: Frrraction generally tries to maintain num/den as a proper fraction.
Now tap '-' (subtract) which of course undoes the add. Then make F2d be a decimal (tap '⋅') and note that "All Integers" at the top has become "Some Decimals"; now tap '+' again and note the different response: this time the result only alters F2d while the other five Fcells remain unchanged—because F2d and its mate F1d are now a decimal pair. Now tap 'x' '/' '-' (multiply then divide then subtract) while keeping an eye on the series of results. Finally, tap '<DEL' to remove the decimal point from F2d then tap the sequence '+' 'x' '/' '-' again. Welcome to Frrraction's basic arithmetic.
Next, tap YellowKey twice then 'M|P|R'. This explains what YellowKey and the 'M|P|R' key are about. Then tap YellowKey once then 'M|P|R' again; now Frrraction\'s MAINview is doing pure fractions (no integer part). With 1/2 still in F1 and 3/5 still in F2, tap '+' again; notice that there was no carry into the now-inactive F2i, and F2n/F2d remains pure but is no longer a proper fraction. Tap '-' to restore F2=3/5.\n\nNow tap 'M|P|R' once more (yes, you always first tap YellowKey before tapping a yellow function key, so we won't always bother to say so). F2d (now labeled M2 indicating that it's now a modulus, not a denomina-tor) is still the active Fcell. Tap some arithmetic keys while watching Modular-Field 2 and hShow; it may take some reading about modular residue arithmetic before the results make sense, but there you have it. Tap 'M|P|R' once more to get MAIN back to normal. Welcome to Frrraction's not-entirely-basic arithmetic.
For a glimpse of Frrraction far beyond its basic arithmetic, switch to Frrraction's PROGramming view by tapping 'PROG'. You might want to tap the pre-loaded '<|5|' key to see what it's like to load and EXECecute a frrrApp program. When you're ready, tap MAIN to switch back to MAINview.
The next thing I recommend for getting familiar with Frrraction is to go through all fifteen of the yellow function keys, tapping Y Y 1, Y Y 2, Y Y 3 and so on across the digit strip and up the op strip, and read the little Help message that shows up each time. When you finish that, you've covered the basics of the App.
When you're ready to dig deeper, go to the full guide: