The first crate of the sweep, so the layout can be checked before the
remaining forty. English paragraph, empty doc line, then the Chinese, per
the glossary. Terms with a standard Chinese name use it directly, so
semi-major axis reads 半长轴 rather than carrying the English each time;
Walker, SGP4 and the frame abbreviations stay as they are.
Every comment block in the crate now has both languages, the Display
strings are untouched because translating them would change what a program
prints, and the three formulas the comments state were checked against the
code: the phase offset is 2 pi f / t, the plane spacing 2 pi / p, and the
anomaly spacing 2 pi / (t / p), all of which match.
The search binary searches the sample list to interpolate between the two
samples that straddle a crossing, and a binary search over an unordered
list returns a wrong index instead of failing. Only the first and last
times were checked, so a sequence whose ends were in order but whose
middle was not refined each crossing against the wrong pair of positions
and reported a pass that never happened. On a circular ground track,
shuffling two samples changed the result from three passes to two and
still returned Ok.
The whole sequence is now checked, with a new UnorderedSamples error kind
that says which pair is out of order. The test covers the middle-of-
sequence case that the end check missed.
Two comments also described something other than what the code does, and
two Option-returning accessors did not say what makes them None:
- GravityModel::x2o3 is the constant 2/3, used as an exponent in the
mean motion and drag corrections, not 2 * xke^2 as its comment claimed;
the sgp4 reference implementation uses the same constant the same way.
- WalkerPattern::plane_spacing and phase_offset returned None without
saying so, which is the case a caller has to handle.
Both READMEs claimed twelve expect sites where there are thirteen, because
apsis-math/src/parallel.rs added one and the count was not carried over.
The parallelism note linked to a type the module does not import, which
rustdoc rejects, so it reads as plain text now. The access batch test
computed a propagated state it did not use; it now takes the shell radius
from it so the track sits at a realistic altitude.
A single visibility test costs a few nanoseconds, so the thread start up is
only repaid by a large matrix. Measured on sixteen cores the parallel form
gains from a few hundred satellites and loses below that, so the note says
so and points a small shell at the sequential form.
Building a topology asks the same geometry question for every pair of
satellites, which is a quadratic number of independent tests, and that loop
is the dominant cost of the construction. The parallel form returns the
same row major matrix in the same order as the sequential one.
A ground station's access schedule is one search per satellite, each
independent of the others, and a shell gives enough of them to pay for the
threads. The parallel form returns the same summaries in the same order as
the sequential one, including an error at the position the sequential form
would put it, so one bad track does not hide the rest.
Asking whether an edge already exists scanned the whole edge list, so
building a graph of E edges cost O(E^2). A visibility sweep adds a quadratic
number of edges, so the whole construction was cubic: 600 satellites took
twelve seconds. An index of outgoing edge positions makes the membership
test constant time, and the same index answers neighbours and out-degree
without a scan. Removal rebuilds the index in one pass, since it renumbers
every later position. Six hundred satellites now take 130 ms, a factor of
ninety five.
Running rustdoc with -D warnings found nine broken links: a misspelt
WGS84, links to methods and constants that are private or in a crate that
is not a dependency, and three redundant explicit targets. Fix each and add
a documentation step to CI so a doc comment cannot drift away from the code
it describes without the build noticing.
Thirty four crates listed apsis-core or apsis-math without referencing it,
and apsis-kepler listed apsis-time and apsis-tle as well. Each was verified
removable by compiling with it taken out. An unused dependency still costs
build time and makes the dependency graph and the layer check report
relations that do not exist. The layer check now reports 104 edges, down
from 141.
ApsisRS contributors