perf_cat.jl

function cat2d_perf(n, iter)
    a = rand(n,n)
    b = rand(n,n)
    for i=1:iter
        c = [a b; b a]
    end
end

function cat2d_perf2(n, iter)
    a = rand(n,n)
    b = rand(n,n)
    for i=1:iter
        c = Array(Float64, 2n, 2n)
        c[1:n,1:n] = a
        c[1:n,n+1:end] = b
        c[n+1:end,1:n] = b
        c[n+1:end,n+1:end] = a
        #c = [a b; b a]
    end
end

@timeit cat2d_perf(5, 20000) "small cat"
@timeit cat2d_perf2(5, 20000) "small cat 2"

@timeit cat2d_perf(500, 2) "large cat"
@timeit cat2d_perf2(500, 2) "large cat 2"

function hcat_perf(n, iter)
    a = rand(n,n)
    b = rand(n,n)
    for i=1:iter
        c = [a b b a]
    end
end

function hcat_perf2(n, iter)
    a = rand(n,n)
    b = rand(n,n)
    for i=1:iter
        c = Array(Float64, n, 4n)
        c[:, 1:n] = a
        c[:, n+1:2n] = b
        c[:, 2n+1:3n] = b
        c[:, 3n+1:end] = a
    end
end

@timeit hcat_perf(5, 20000) "small hcat"
@timeit hcat_perf2(5, 20000) "small hcat 2"

@timeit hcat_perf(500, 2) "large hcat"
@timeit hcat_perf2(500, 2) "large hcat 2"

function vcat_perf(n, iter)
    a = rand(n,n)
    b = rand(n,n)
    for i = 1:iter
        c = [a, b, b, a]
    end
end

function vcat_perf2(n, iter)
    a = rand(n,n)
    b = rand(n,n)
    for i=1:iter
        c = Array(Float64, 4n, n)
        c[1:n, :] = a
        c[n+1:2n, :] = b
        c[2n+1:3n, :] = b
        c[3n+1:4n, :] = a
    end
end

@timeit vcat_perf(5, 20000) "small vcat"
@timeit vcat_perf2(5, 20000) "small vcat 2"

@timeit vcat_perf(500, 2) "large vcat"
@timeit vcat_perf2(500, 2) "large vcat 2"

function catnd_perf(n, iter)
    a = rand(1,n,n,1)
    b = rand(1,n,n)
    for i = 1:iter
        c = cat(3, a, b, b, a)
    end
end

function catnd_perf2(n, iter)
    a = rand(1,n,n,1)
    b = rand(1,n,n)
    for i = 1:iter
        c = Array(Float64, 1, n, 4n, 1)
        c[1,:,1:n,1] = a
        c[1,:,n+1:2n,1] = b
        c[1,:,2n+1:3n,1] = b
        c[1,:,3n+1:4n,1] = a
    end
end

@timeit catnd_perf(5, 20000) "small catnd"
@timeit catnd_perf2(5, 20000) "small catnd 2"

@timeit catnd_perf(500, 2) "large catnd"
@timeit catnd_perf2(500, 2) "large catnd 2"