Resources Numerical accuracy Calculation policy
The numbers the assistant tools return for radio links and coverage, and the coverage read-out in the geotechnical and telecom window.
The assistant rounds every number it returns to 3 decimals in the unit it reports. The coverage grid of received power is a Float32Array, and both the coverage map values and the farthest-covered distance are taken from it.
Open item. Return the received power from telecom.js coverage in a Float64Array so the covered decision and the farthest distance are made on 64-bit values.
4 calculations in 2 source files. The code is read from the released app when this page loads. It is the calculation people run, not a copy kept for this page.
Tests None found by the review
Rounds a result to 3 decimals before the assistant is given it.
round(v × 1000) ÷ 1000
The value is rounded to a step of 0.001 in whatever unit the tool reports (meters, feet, kN, dB, km). Non-finite values become null, and Infinity becomes the text 'infinite'.
const r3 = (v) => (Number.isFinite(v) ? Math.round(v * 1000) / 1000 : v === Infinity ? 'infinite' : null);The distance, loss, received power, fade margin and availability the assistant reports for a radio link.
annual unavailability = round(U × 1e6 × 1000) ÷ 1000 ÷ 1e6
The values come from runLink as 64-bit numbers and are rounded for the assistant to 0.001, except availability, which is first scaled by 1e6 so the rounding step is 1e-9. Tower shear and moment are divided by 1000 to kN and kN·m before rounding.
run: (a) => { const r = runLink(find('links', a.link, 'link'), U(), ground()); return { note: AID, distanceKm: r3(r.dKm), freeSpaceLossDb: r3(r.fspl), receivedDbm: r3(r.budget.pr), fadeMarginDb: r3(r.budget.margin), lineOfSightClear: r.los.clear, tightest: r.los.min && { atKm: r3(r.los.min.d), clearance: r3(r.los.min.clearance), fresnelRadius: r3(r.los.min.F1), clearanceOverFresnel: r3(r.los.min.ratio) }, mastHeightAtA: r3(r.mast), availability: { annualUnavailability: r3(r.availability.annual * 1e6) / 1e6, worstMonth: r3(r.availability.worstMonth * 1e6) / 1e6, minutesPerYear: r3(r.availability.secondsPerYear / 60), method: 'Vigants-Barnett multipath, no rain' }, tower: r.tower && { shearKN: r3(r.tower.shear / 1000), momentKNm: r3(r.tower.moment / 1000), overturnFactor: r3(r.tower.fsOverturn) }, towerLegs: r.legs && { note: 'statics only; your tower code decides', compressionKN: r3(r.legs.compression), upliftKN: r3(r.legs.tension), useOfCapacity: r.legs.utilization === null ? null : r3(r.legs.utilization), eulerLoadKN: r.legs.pcr === null ? null : r3(r.legs.pcr), bucklingUse: r.legs.bucklingUtil === null ? null : r3(r.legs.bucklingUtil) }, findings: codes(r.problems) }; } },The share of the area covered, the farthest covered point and a coarse map of received power.
map cell = r3(p) when p ≥ sensitivity, else null
Each map value p is read from the 32-bit grid r.pr, compared with the sensitivity, and rounded to 3 decimals, so the value shown is a 32-bit number rounded. The farthest-covered distance came from runCover, which also picks covered cells from the 32-bit grid.
run: (a) => { const c = find('covers', a.cover, 'coverage'), r = runCover(c, U(), ground()); if (!r.ok) throw new ToolErr('failed', 'Too many cells for that radius and cell size (' + r.problems[0].cells + ').', ['Use a larger cell size.']);
const stride = Math.max(1, Math.ceil(r.nx / 40)), rows = []; for (let j = 0; j < r.ny; j += stride) { const row = []; for (let i = 0; i < r.nx; i += stride) { const p = r.pr[i + r.nx * j]; row.push(p >= c.sensitivity ? r3(p) : null); } rows.push(row); }
return { note: AID, units: { length: U() }, coveredShare: r3(r.covered), farthestCovered: r3(r.farthest), cellsOverKnownGround: r.cells, cellSize: c.step, mapStride: stride, mapDbm: rows, findings: codes(r.problems) }; } },Tests None found by the review
The share covered, the farthest covered distance and the cell count shown for a coverage item.
covered % = covered × 100; farthest = distance as returned
The window multiplies the covered fraction from telecom.js coverage by 100 and prints 1 decimal, and prints the farthest distance with no decimals. That distance is chosen in geo-run.js runCover by testing the 32-bit grid value against the sensitivity.
return [svg(coverSvg(c, r)), kv([[t('geo.cover.covered'), fixed(r.covered * 100, 1) + ' %'], [t('geo.cover.farthest'), fixed(r.farthest, 0) + ' ' + lenU()], [t('geo.cover.cells'), String(r.cells)]]), note(t('geo.cover.note'))];One step stores or exchanges 32-bit values that reach a number a person reads. It is listed here with its open item, and the step is either moved to 64-bit or the app will warn where the number is read.