Entry
Bearings are entered in D.MMSS. A bearing of
42°01′36″ is typed as 42.0136. Distances
are metres.
A bearing delta is added to every new leg's bearing before it is stored. Use
it to swing a whole traverse onto a datum.
The distance field takes arithmetic, and these functions:
- sin(x), cos(x),
tan(x)
- asin(x), acos(x),
atan(x)
- sqrt(x), pow(x, y)
- pi, e
And these units, converted to metres on entry:
- in — inch, 0.0254
- ft — foot, 0.3048
- yd — yard, 0.9144
- li — link, 0.201168
- ch — chain, 20.1168
So 100li + 2ch reduces to 60.350 m.
Distances are stored at full precision and shown to three decimal places.
Reduction
The closure is a direct vector sum. No adjustment is applied.
- Each leg is treated as a vector of its bearing and distance.
- Legs are summed sequentially from a common origin.
- The misclose is the vector from the final point back to the start.
- Its distance is the closure error; its bearing is the direction of that error, and the
reverse is that bearing plus 180°.
- Accuracy is quoted as a ratio of total traverse length to misclose, or as parts per
million. The threshold is set in Settings.
A leg whose bearing runs parallel to the closure is tinted in the table. It is the leg most
likely to carry the blunder — check it first.
Features
- Add legs — enter a bearing and a distance, then Add leg.
- Edit and delete — Edit changes a leg in place; More inserts a leg above or
below, or deletes one.
- Reverse — flips a single leg's bearing by 180°.
- Reorder — drag the handle at the left of a row.
- History — the last ten traverses, restorable.
- Plot — the traverse and its closure drawn on plane coordinates.
Everything is saved as you work.
Install
This is a progressive web app. It works offline after the first visit and updates itself in
the background.
- Android, Chrome — browser menu, then
Add to Home screen.
- iOS, Safari — the share control, then
Add to Home Screen.
- Desktop — the install control in the address bar.