added docstring for boost vectors

src/lorentz_boost/axis_boost.jl

@@ -1,4 +1,4 @@
-# TODO: 
+# TODO:
 # - test conversions
 # - add convenient constructors: Boost(:x,::Real)
 # - add convenient constructors: Boost(:rest_frame,::AbstractFourMomentum)
@@ -56,7 +56,7 @@ end
 
     BetaX(beta::T) where {T<:Real}
 
-Beta parameter associated to the x-axis, commonly referred to as ``\\beta_x``. 
+Beta parameter associated to the x-axis, commonly referred to as ``\\beta_x``.
 The corresponding Lorentz boost reads
 
 ```math
@@ -80,11 +80,6 @@ where the kinematic factor is given as ``\\gamma = 1/\\sqrt{1-\\beta_x^2}``)
 ```jldoctest
 julia> using QEDcore
 
-julia> using Random
-
-julia> RNG = MersenneTwister(1234)
-MersenneTwister(1234)
-
 julia> beta_x = BetaX(0.5)
 BetaX{Float64}(0.5)
 
@@ -105,7 +100,7 @@ julia> p_prime = boost(p)
  2.0
  1.0
 
-julia> @assert isapprox(p*p,p_prime*p_prime) 
+julia> @assert isapprox(p*p,p_prime*p_prime)
 ```
 
 ## External link
@@ -137,7 +132,7 @@ end
 
     BetaY(beta::T) where {T<:Real}
 
-Beta parameter associated to the y-axis, commonly referred to as ``\\beta_y``. 
+Beta parameter associated to the y-axis, commonly referred to as ``\\beta_y``.
 The corresponding Lorentz boost reads
 
 ```math
@@ -186,7 +181,7 @@ julia> p_prime = boost(p)
  0.0
  1.0
 
-julia> @assert isapprox(p*p,p_prime*p_prime) 
+julia> @assert isapprox(p*p,p_prime*p_prime)
 ```
 
 ## External link
@@ -218,7 +213,7 @@ end
 
     BetaZ(beta::T) where {T<:Real}
 
-Beta parameter associated to the z-axis, commonly referred to as ``\\beta_z``. 
+Beta parameter associated to the z-axis, commonly referred to as ``\\beta_z``.
 The corresponding Lorentz boost reads
 
 ```math
@@ -267,7 +262,7 @@ julia> p_prime = boost(p)
   2.0
  -1.1547005383792517
 
-julia> @assert isapprox(p*p,p_prime*p_prime) 
+julia> @assert isapprox(p*p,p_prime*p_prime)
 
 ```
 

src/lorentz_boost/boost_vector.jl

@@ -1,15 +1,76 @@
 
-# TODO: 
+# TODO:
 # - add interaction with axis boosts
 # - add convenient constructors BetaVector(p) for the rest system?
 # - test constructor error
 """
-TBW
+
+    AbstractBoostVector<:AbstractBoostParameter
+
+Abstract base type for vector-like boost parameters, modelling boosts in any spatial dimension.
 """
 abstract type AbstractBoostVector <: AbstractBoostParameter end
 
 """
-TBW
+
+    BetaVector(x::Real,y::Real,z::Real)
+
+Spatial vector of beta parameters associated with the three chartesian directions: ``\\vec\\beta = (\\beta_x,\\beta_y,\\beta_z)``.
+The corresponding Lorentz boost transformation reads
+
+```math
+\\begin{pmatrix}
+p_0\\\\
+p_1\\\\
+p_2\\\\
+p_3
+\\end{pmatrix} \\mapsto
+\\begin{pmatrix}
+    \\gamma  (p_0 - \\vec\\beta \\vec p)\\\\
+p_1 + (\\frac{\\gamma - 1}{\\beta^2} \\vec\\beta\\vec p - \\gamma  p_0)
+ \\beta_x\\\\
+p_2 + (\\frac{\\gamma - 1}{\\beta^2} \\vec\\beta\\vec p - \\gamma  p_0)
+ \\beta_y\\\\
+    p_3 + (\\frac{\\gamma - 1}{\\beta^2} \\vec\\beta\\vec p - \\gamma  p_0)
+ \\beta_z\\\\
+\\end{pmatrix}
+```
+where the kinematic factor is given as ``\\gamma = 1/\\sqrt{1-\\beta_x^2}``)
+
+## Example
+
+```jldoctest
+julia> using QEDcore
+
+julia> beta_vec = BetaVector(0.2,0.3,0.1)
+BetaVector{Float64}(0.2, 0.3, 0.1)
+
+julia> boost = Boost(beta_vec)
+Boost{BetaVector{Float64}}(BetaVector{Float64}(0.2, 0.3, 0.1))
+
+julia> p = SFourMomentum(4.0,3.0,2.0,1.0)
+4-element SFourMomentum with indices SOneTo(4):
+ 4.0
+ 3.0
+ 2.0
+ 1.0
+
+julia> p_prime = boost(p)
+4-element SFourMomentum with indices SOneTo(4):
+ 2.911484876492837
+ 2.282803602436349
+ 0.9242054036545237
+ 0.6414018012181746
+
+julia> @assert isapprox(p*p,p_prime*p_prime)
+```
+
+## External link
+
+* [Lorentz Boost on Wikipedia](https://en.wikipedia.org/wiki/Lorentz_transformation)
+* [Kinematics in PDG review](https://pdg.lbl.gov/2024/reviews/rpp2024-rev-kinematics.pdf)
+* [`ROOT::Math:Boost` from ROOT](https://root.cern.ch/doc/master/classROOT_1_1Math_1_1Boost.html)
+
 """
 struct BetaVector{T<:Real} <: AbstractBoostVector
     x::T

src/lorentz_boost/types.jl

@@ -5,20 +5,20 @@
 """
     AbstractCoordinateTransformation
 
-Abstract base type for coordinate transformations supposed to be acting on four-momenta. 
+Abstract base type for coordinate transformations supposed to be acting on four-momenta.
 Every subtype of `trafo::AbstractCoordianteTransformation` should implement the following interface functions:
 
 * `QEDcore._transform(trafo,p)`: transfroms `p`
 * `Base.inv(trafo)`: returns the inverted transform
 
 ## Example
 
-Implementing the interface by defining the interface functions: 
+Implementing the interface by defining the interface functions:
 
 ```jldoctest trafo_interface
 julia> using QEDcore
 
-julia> struct TestTrafo{T} <: QEDcore.AbstractCoordinateTransformation   
+julia> struct TestTrafo{T} <: QEDcore.AbstractCoordinateTransformation
            a::T
        end
 
@@ -41,14 +41,14 @@ julia> p = SFourMomentum(4,3,2,1)
  2.0
  1.0
 
-julia> trafo(p)
+julia> trafo(p) # multiply every component with 2.0
 4-element SFourMomentum with indices SOneTo(4):
  8.0
  6.0
  4.0
  2.0
 
-julia> inv(trafo)(p)
+julia> inv(trafo)(p) # divide every component by 2.0
 4-element SFourMomentum with indices SOneTo(4):
  2.0
  1.5
@@ -62,7 +62,7 @@ Base.broadcastable(trafo::AbstractCoordinateTransformation) = Ref(trafo)
 """
     _transform(trafo::AbstractCoordinateTransformation,p::AbstractFourMomentum)
 
-Interface function for the application of the transformation to the four-momentum `p`. Must return a four-momentum 
+Interface function for the application of the transformation to the four-momentum `p`. Must return a four-momentum
 of the same type as `p`.
 """
 function _transform end
@@ -123,7 +123,7 @@ boost_type(::Boost{V}) where {V} = V
 Boost(x::Real) = Boost(BetaX(x))
 Boost(x::Real, y::Real, z::Real) = Boost(BetaVector(x, y, z))
 
-# TODO: 
+# TODO:
 # - add more convenient functions (type of the boost_param, ... )
 # - interaction between several boosts? -> product trafo (for later)