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add EclipticCoords #46

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Feb 11, 2023
Merged

add EclipticCoords #46

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e1af8a5
add EclipticCoords
aplavin Dec 23, 2022
97bb96f
fix
aplavin Jan 13, 2023
04d5038
add tests
aplavin Jan 13, 2023
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17 changes: 17 additions & 0 deletions src/SkyCoords.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@ export AbstractSkyCoords,
ICRSCoords,
GalCoords,
FK5Coords,
EclipticCoords,
CartesianCoords,
separation,
position_angle,
Expand Down Expand Up @@ -101,11 +102,20 @@ function precess_from_j2000(equinox)
zrotmat(-z) * yrotmat(theta) * zrotmat(-zeta)
end

function ecliptic_obliquity(y)
# https://github.com/JuliaAstro/AstroBase.jl/blob/master/src/EarthAttitude/obliquity.jl
T = (y - 2000.0) / 100
obl = @evalpoly(T, 84381.406, -46.836769, -0.0001831, 0.00200340, -0.000000576, -0.0000000434)
return deg2rad(obl / 3600)
end

# -----------------------------------------------------------------------------
# Type-dependent methods

lon(c::GalCoords) = c.l
lat(c::GalCoords) = c.b
lat(c::EclipticCoords) = c.lat
lon(c::EclipticCoords) = c.lon
lon(c::AbstractSkyCoords) = c.ra
lat(c::AbstractSkyCoords) = c.dec

Expand All @@ -121,6 +131,13 @@ rotmat(::Type{<:ICRSCoords}, ::Type{<:ICRSCoords}) = I
rotmat(::Type{<:GalCoords}, ::Type{<:GalCoords}) = I
rotmat(::Type{<:FK5Coords{e}}, ::Type{<:FK5Coords{e}}) where {e} = I

@generated rotmat(::Type{<:EclipticCoords{e}}, ::Type{<:FK5Coords{e}}) where {e} = xrotmat(ecliptic_obliquity(e))
@generated rotmat(::Type{<:FK5Coords{e}}, ::Type{<:EclipticCoords{e}}) where {e} = xrotmat(-ecliptic_obliquity(e))
@generated rotmat(::Type{<:EclipticCoords{e}}, ::Type{T}) where {e,T<:AbstractSkyCoords} = rotmat(EclipticCoords{e}, FK5Coords{e}) * rotmat(FK5Coords{e}, T)
@generated rotmat(::Type{T}, ::Type{<:EclipticCoords{e}}) where {e,T<:AbstractSkyCoords} = rotmat(T, FK5Coords{e}) * rotmat(FK5Coords{e}, EclipticCoords{e})
# disambiguation:
@generated rotmat(::Type{<:EclipticCoords{e_to}}, ::Type{<:EclipticCoords{e_from}}) where {e_to,e_from} = rotmat(EclipticCoords{e_to}, FK5Coords{e_to}) * rotmat(FK5Coords{e_to}, EclipticCoords{e_from})

@generated rotmat(::Type{<:FK5Coords{e1}}, ::Type{<:ICRSCoords}) where {e1} =
precess_from_j2000(e1) * ICRS_TO_FK5J2000
@generated rotmat(::Type{<:FK5Coords{e1}}, ::Type{<:GalCoords}) where {e1} =
Expand Down
13 changes: 13 additions & 0 deletions src/types.jl
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Expand Up @@ -72,6 +72,18 @@ FK5Coords{e,F}(c::T) where {e,F,T<:AbstractSkyCoords} = convert(FK5Coords{e,F},
constructorof(::Type{<:FK5Coords{e}}) where {e} = FK5Coords{e}


struct EclipticCoords{e,T<:AbstractFloat} <: AbstractSkyCoords
lon::T
lat::T
EclipticCoords{e,T}(lon, lat) where {e,T<:AbstractFloat} = new(mod2pi(lon), lat)
end
EclipticCoords{e}(lon::T, lat::T) where {e,T<:AbstractFloat} = EclipticCoords{e,T}(lon, lat)
EclipticCoords{e}(lon::Real, lat::Real) where {e} = EclipticCoords(promote(float(lon), float(lat))...)
EclipticCoords{e}(c::AbstractSkyCoords) where {e} = convert(EclipticCoords{e}, c)
EclipticCoords{e,F}(c::AbstractSkyCoords) where {e,F} = convert(EclipticCoords{e,F}, c)
constructorof(::Type{<:EclipticCoords{e}}) where {e} = EclipticCoords{e}


# Scalar coordinate conversions
Base.convert(::Type{T}, c::T) where {T<:AbstractSkyCoords} = c

Expand All @@ -85,3 +97,4 @@ Base.:(==)(a::T, b::T) where {T<:AbstractSkyCoords} = lon(a) == lon(b) && lat(a)
Base.isapprox(a::ICRSCoords, b::ICRSCoords; kwargs...) = isapprox(SVector(lon(a), lat(a)), SVector(lon(b), lat(b)); kwargs...)
Base.isapprox(a::GalCoords, b::GalCoords; kwargs...) = isapprox(SVector(lon(a), lat(a)), SVector(lon(b), lat(b)); kwargs...)
Base.isapprox(a::FK5Coords{e}, b::FK5Coords{e}; kwargs...) where {e} = isapprox(SVector(lon(a), lat(a)), SVector(lon(b), lat(b)); kwargs...)
Base.isapprox(a::EclipticCoords{e}, b::EclipticCoords{e}; kwargs...) where {e} = isapprox(SVector(lon(a), lat(a)), SVector(lon(b), lat(b)); kwargs...)
16 changes: 9 additions & 7 deletions test/astropy.jl
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Expand Up @@ -12,8 +12,9 @@ const lats = pi .* (rand(rng, N) .- 0.5) # (-π, π)
astropy_conversion(::Type{<:ICRSCoords}) = apc.ICRS
astropy_conversion(::Type{<:FK5Coords{F}}) where {F} = apc.FK5(equinox="J$F")
astropy_conversion(::Type{<:GalCoords}) = apc.Galactic
astropy_conversion(::Type{<:EclipticCoords{F}}) where {F} = apc.GeocentricMeanEcliptic(equinox="J$F")

function test_against_astropy(intype, outtype)
function test_against_astropy(intype, outtype; atol=0)
## get julia values
output_coords = map((lon, lat) -> convert(outtype, intype(lon, lat)), lons, lats)
output_lons = map(lon, output_coords)
Expand All @@ -28,8 +29,8 @@ function test_against_astropy(intype, outtype)
ap_output_lons = pyconvert(Vector, output_coord_list.spherical.lon.rad)
ap_output_lats = pyconvert(Vector, output_coord_list.spherical.lat.rad)

@test output_lons ≈ ap_output_lons
@test output_lats ≈ ap_output_lats
@test output_lons ≈ ap_output_lons atol=atol*√N
@test output_lats ≈ ap_output_lats atol=atol*√N

end

Expand All @@ -47,10 +48,11 @@ end
FK5Coords{2000,F},
FK5Coords{1975,F},
GalCoords{F},
EclipticCoords{2000,F},
EclipticCoords{1975,F},
)

@testset "$IN_SYS --> $OUT_SYS"for IN_SYS in systems, OUT_SYS in systems
test_against_astropy(IN_SYS, OUT_SYS)

@testset "$IN_SYS --> $OUT_SYS" for IN_SYS in systems, OUT_SYS in systems
atol = IN_SYS <: EclipticCoords || OUT_SYS <: EclipticCoords ? 1e-3 : 0
test_against_astropy(IN_SYS, OUT_SYS; atol)
end
end