init commit

.gitignore

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+
+# Created by https://www.toptal.com/developers/gitignore/api/vscode,julia
+# Edit at https://www.toptal.com/developers/gitignore?templates=vscode,julia
+
+### Julia ###
+# Files generated by invoking Julia with --code-coverage
+*.jl.cov
+*.jl.*.cov
+
+# Files generated by invoking Julia with --track-allocation
+*.jl.mem
+
+# System-specific files and directories generated by the BinaryProvider and BinDeps packages
+# They contain absolute paths specific to the host computer, and so should not be committed
+deps/deps.jl
+deps/build.log
+deps/downloads/
+deps/usr/
+deps/src/
+
+# Build artifacts for creating documentation generated by the Documenter package
+docs/build/
+docs/site/
+
+# File generated by Pkg, the package manager, based on a corresponding Project.toml
+# It records a fixed state of all packages used by the project. As such, it should not be
+# committed for packages, but should be committed for applications that require a static
+# environment.
+Manifest.toml
+
+### vscode ###
+.vscode/*
+*.code-workspace
+
+# End of https://www.toptal.com/developers/gitignore/api/vscode,julia

Project.toml

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+name = "AstroHelper"
+uuid = "e9cfef36-66ad-4d03-9ce9-ac75942e61e4"
+authors = ["Anson <anson@ansonbiggs.com>"]
+version = "0.1.0"
+
+[deps]
+LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"

src/AstroHelper.jl

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+module AstroHelper
+using LinearAlgebra
+
+
+include("Quaternions.jl")
+
+end # module

src/Quaternions.jl

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+struct Quaternion
+	i::Float64
+	j::Float64
+	k::Float64
+	r::Float64
+	
+	Quaternion(i, j, k, r) = norm([i, j, k, r]) ≈ 1 ? new(i, j, k, r) : error("Magnitude not equal to 1.") 
+	Quaternion(q) = Quaternion(q[1], q[2], q[3], q[4]) 
+	Quaternion() = new(0, 0, 0, 1)
+	
+	# Quaternion(ē, ϕ) = Quaternion(vcat(if sum(ē) == 0 ? [0 0 0] : ē / norm(ē) * sin(ϕ / 2),cos(ϕ / 2)))
+	function Quaternion(ē, ϕ)
+		if sum(ē) == 0
+			return Quaternion([0 0 0 cos(ϕ / 2)])
+		end
+		dir = normalize(ē) * sin(ϕ / 2)
+		return Quaternion(dir[1], dir[2], dir[3], cos(ϕ / 2))
+	end
+	
+end
+
+function QuaternionMultiplication(l::Quaternion, r::Quaternion)
+	R = [r.r r.k r.j r.i;
+		 -r.k r.r r.i r.j;
+		 r.j -r.i r.r r.k;
+		 -r.i -r.j -r.k r.r]
+	L = [l.i; l.j; l.k; l.r]
+	return Quaternion(R * L)
+	
+end
+
+Base.:*(l::Quaternion, r::Quaternion) = QuaternionMultiplication(l::Quaternion, r::Quaternion)
+
+Base.iterate(q::Quaternion) = (q.i, 1)
+Base.iterate(q::Quaternion, state=1) = state > 4 ? nothing : ([q.i q.j q.k q.r][state], state + 1)
+Base.length(q::Quaternion) = 4
+Base.collect(q::Quaternion) = [q.i q.j q.k q.r]
+Base.getindex(q::Quaternion, i) = collect(q)[i]
+Base.isapprox(a::Quaternion,b::Quaternion) = isapprox(collect(a), collect(b))
+
+LinearAlgebra.norm(q::Quaternion) = norm(collect(q))
+LinearAlgebra.normalize(q::Quaternion) = collect(q) / norm(q)
+# q = Quaternion([1,-2,2], -2 * pi / 3) * Quaternion([0,0,0,1])
+
+# println(q[3])

test/Project.toml

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+[deps]
+Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"

test/runtests.jl

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+using AstroHelper
+using Test
+
+import AstroHelper: Quaternion
+
+@testset "Quaternion Initialization" begin
+    @test Quaternion().r == 1.0
+    @test Quaternion([0,0,0,1]) == Quaternion(0, 0, 0, 1)
+    @test Quaternion([0 0 0], 0) == Quaternion(0, 0, 0, 1)
+    @test Quaternion([1 -2 2], (-2 * pi / 3)) ≈ Quaternion([-sqrt(3) / 6, sqrt(3) / 3, -sqrt(3) / 3, 1 / 2])
+    @test_throws ErrorException Quaternion(1, 2, 3, 4)
+end