Merge pull request #496 from rfourquet/reduce-vcat

optimize reduce(vcat, vector_of_matrices)

Author: wbhart

src/generic/Matrix.jl

@@ -4797,6 +4797,8 @@ function Base.vcat(A::MatrixElem...)
   return _vcat(A)
 end
 
+Base.reduce(::typeof(vcat), A::AbstractVector{<:MatrixElem}) = _vcat(A)
+
 function _vcat(A)
   if length(A) == 0
     error("Number of matrices to concatenate must be positive")
@@ -4832,6 +4834,8 @@ function Base.hcat(A::MatrixElem...)
   return _hcat(A)
 end
 
+Base.reduce(::typeof(hcat), A::AbstractVector{<:MatrixElem}) = _hcat(A)
+
 function _hcat(A)
   if length(A) == 0
     error("Number of matrices to concatenate must be positive")

test/generic/Matrix-test.jl

@@ -2006,6 +2006,7 @@ end
                                   0 1 0;
                                   0 1 2;])
    @test hcat(B, C) == [B C]
+   @test hcat(B, C, C, B) == reduce(hcat, [B, C, C, B])
    let BC = hcat([B, C])
       @test size(BC) == (2, 1)
       @test BC[1] == B
@@ -2020,13 +2021,13 @@ end
                                   0 1;])
 
    @test vcat(A, B) == [A; B]
+   @test vcat(A, B, B, A) == reduce(vcat, [A, B, B, A])
    let AB = vcat([A, B])
       @test size(AB) == (2,)
       @test AB[1] == A
       @test AB[2] == B
    end
 
-
    @test [A D; B B C] == matrix(R, [1 2 1 2 3;
                                     3 4 4 5 6;
                                     1 2 1 2 0;