Tech Note F
Every control in the Settings card
Rounding, the four Display ticks and the AC power convention, each with what it changes, what it does not, and why two of them appear only in AC.
Last updated 2026-09-11
Nothing in Settings changes an answer. Every control there changes how an answer is written — how many figures it carries, whether it wears a unit, whether a complex number is shown as a phasor. The one exception is the AC power convention at the foot of the card, which changes what the average power in an AC circuit means, and is called out below.
The lessons reach for these controls as they need them. This note is the whole card in one place, for when you want to know what a tick does without hunting for the lesson that first used it.
Rounding
A menu of four, most exact first, with a second box for n that appears only when the choice needs one.
| Choice | What you get |
|---|---|
| exact | The symbolic answer, unrounded: a current comes back as 3/500 A |
| exact and approx to n digits | Both, side by side, for any answer that is a pure number |
| approx to n digits | The decimal alone, to n significant figures |
| approx (full precision) | The decimal alone, at full working precision |
n takes 2 to 12 and starts at 4. A symbolic answer has nothing to approximate and is left exact under every choice, so exact and approx shows one value for x*vin/(r1 + x) and two for 0.006.
The rounding is done in decimal, not in binary, so the last digit is the one you would write by hand.
Display
Four ticks, and they are independent of each other except where noted.
Show units in answers — V, A, W, VA, Ω. On by default. Quantities with no unit to show, such as a power factor or a gain, stay bare whatever this says.
Use SI prefixes in answers — 0.002 becomes 2 m, 1200 becomes 1.2 k. Off by default. It applies to numeric answers only; a symbolic answer is left as it is. “SI prefixes” has the full table, and the same shorthand for values you type. Either mu works for micro, whichever your keyboard gives you.
Show AC answers as polar phasors — 3 + 4j becomes 5∠53.13°. Average power stays real either way, being a real quantity. This tick appears only in AC: in DC every answer is real, and in FD and TR the answers are functions of s or t, with no angle to take.
Show equations — adds an Equations card listing the system the solver assembled. Off by default, because on anything larger than a teaching circuit that system is a page of algebra. The card arrives open when it appears.
AC power convention
RMS phasors. Off means peak amplitude — the ÷2 convention. It affects AC power only, so the row appears in AC and nowhere else.
This is the one setting on the card that changes an answer rather than its appearance. For the same phasor magnitudes, RMS reports twice what peak does — a source of 10 V across a 5 Ω resistor gives 10 W with the tick off and 20 W with it on — and the answer is labelled average power under the peak convention and power consumed under RMS. Set it to match the book you are working from before comparing numbers.