add docs

Author: dlfivefifty

src/oneelement.jl

@@ -1,6 +1,9 @@
 """
-    OneElement(val, ind, axes) <: AbstractArray
-Extremely simple `struct` used for the gradient of scalar `getindex`.
+    OneElement(val, ind, axesorsize) <: AbstractArray
+
+Represents an array with the specified axes (if its a tuple of `AbstractUnitRange`s)
+or size (if its a tuple of `Integer`s), with a single entry set to `val` and all others equal to zero,
+specified by `ind``.
 """
 struct OneElement{T,N,I,A} <: AbstractArray{T,N}
   val::T
@@ -10,10 +13,26 @@ struct OneElement{T,N,I,A} <: AbstractArray{T,N}
 end
 
 OneElement(val, inds::NTuple{N,Int}, sz::NTuple{N,Integer}) where N = OneElement(val, inds, oneto.(sz))
-OneElement(val, inds::Int, sz::Int) = OneElement(val, (inds,), (sz,))
+"""
+    OneElement(val, ind::Int, n::Int)
+
+Creates a length `n` vector where the `ind` entry is equal to `val`, and all other entries are zero.
+"""
+OneElement(val, ind::Int, len::Int) = OneElement(val, (ind,), (len,))
+"""
+    OneElement(ind::Int, n::Int)
+
+Creates a length `n` vector where the `ind` entry is equal to `1`, and all other entries are zero.
+"""
 OneElement(inds::Int, sz::Int) = OneElement(1, inds, sz)
 OneElement{T}(val, inds::NTuple{N,Int}, sz::NTuple{N,Integer}) where {T,N} = OneElement(convert(T,val), inds, oneto.(sz))
 OneElement{T}(val, inds::Int, sz::Int) where T = OneElement{T}(val, (inds,), (sz,))
+
+"""
+    OneElement{T}(val, ind::Int, n::Int)
+
+Creates a length `n` vector where the `ind` entry is equal to `one(T)`, and all other entries are zero.
+"""
 OneElement{T}(inds::Int, sz::Int) where T = OneElement(one(T), inds, sz)
 
 Base.size(A::OneElement) = map(length, A.axes)