More low-level functions necessary to calculating Earth orientation.
iau2000b calculates nutation angles.
etilt calculates overall axial tilt of the Earth.
era calculates the Earth Rotation Angle.
I'm working toward implementing the GeoMoon function.
I added the following, which are all required to get to that point.
meanObliq
eclOblToEquVec
eclToEquVec
precessionRot
precession
RotateVector
Added the function CalendarFromDays, which converts a UT value to
a calendar date and time.
Added script `rungo` which is a shortcut for compiling and testing
changes to the Go source code template.
Added functions:
DegreesFromRadians
RadiansFromDegrees
AngleBetween
StateVector.Position
StateVector.Velocity
Changed existing functions to pass structs by value,
just like we do in the C code. This is a safety feature
to signal value semantics and a contract not to mutate the
argument state.
Run Go tests with the -v option to log more info about what's happening.
I suddenly realized today that I could eliminate lots of red wavy
lines in the source editor when working on generate/template/astronomy.*
files, by tweaking the $ASTRO_... tokens to look like comments.
For some reason, I didn't think of doing this before now.
I was motivated by the Go language support, where the tokens were
breaking `go fmt`.
Added SVG logo for Go.
Added a table entry for Go examples, source, and documentation.
Sorted the language list in alphabetical order: moved Python last.
I need gomarkdoc to generate identical output whether
I run it locally or in GitHub Actions, to verify that the
build process is working correctly. Hopefully these options
will do the trick.
Following the standard comment format for documentation
comments in Go:
https://go.dev/doc/comment
Later we will figure out how to generate online documentation
from these comments.
Before now, the Python demos were tested in Linux and Mac.
Now they are tested in the Windows environment also.
This will be helpful for any contributors who may wish
to use Windows as a development platform for the Python
version of Astronomy Engine.
Use mypy to check all Python demo programs.
Updated the demos to pass type checking.
There were a couple of small mistakes found, so this was worth the effort.
The demo program ecliptic_of_date.py shows how to
calculate the true ecliptic of date (ECT) angular coordinates
of the Sun, Moon, and planets for an observer somewhere on the Earth.
It calculates the equatorial of date (EQD) coordinates, then uses
a rotation matrix to convert the vector to ECT, then converts
the vector to spherical coordinates: latitude, longitude, and distance.
In Go, all symbols should use PascalCase or camelCase.
Go programmers dislike ALL_UPPER_CASE_WITH_UNDERSCORES.
Use PascalCase for exported/public symbols, camelCase for internal/private symbols.
In general, we should follow the Go Style Guide:
https://google.github.io/styleguide/go/index
I recommend we more closely follow the implementation of the C# code
than the C code for figuring out how to name things.
The C# version of Astronomy Engine is a better reference because
Go allows quasi-object-oriented syntax and uses a similar preferred naming style.
We will use idiomatic error reporting and handling, as described here:
https://go.dev/blog/error-handling-and-go
I removed the "status" fields from all the structs, and deleted
the enumerated type astroStatus. I will add a custom error type later,
and report human-readable error messages as is preferred by Go programmers.
I'm not sure this is going to fix the error, because I'm not
sure how 'go fmt' works. I'm hoping that if I fix the newlines
in the generated code, then format it, under Windows it will
end up exactly like what git does to normalize the line endings
when we clone the repo.
Rework astronomy.go as a module named "astronomy".
Provide a go.mod to define the module.
Add Go as a known programming language to the code generator.
This change affects internal unit testing only.
It does not affect developers who use Astronomy Engine.
Upgraded the HYG database used for verification of
constellation calculations to v 3.5.1.
See conversation at:
https://github.com/astronexus/HYG-Database/issues/21
This reverts commit a7e747c100.
This broke the GitHub Actions automated tests, because they
are using gcc 11 (which does not support level 3 fortification),
and they already predefine another fortification level.
I realize this would also hinder other contributors who
are not using gcc 12. At least I tried it once on my own
system and didn't find any problems, which is nice.
It turns out that GetSystemTimeAsFileTime only returns
time with millisecond resolution.
In order to get microsecond resolution in Astronomy_CurrentTime(),
I had to switch to GetSystemTimePreciseAsFileTime for Windows.
Example output from unit test:
C Test_AstroTime: PASS - realtime increment = 3.143e-07 seconds after 1 iterations.
