reshape-benchmark.jl

using LinearAlgebra
using BenchmarkTools
using StaticArrays
using UnsafeArrays

function rv(ar, n)
    total = 0.0
    for i in 1:n
        a = reshape(view(ar, (i-1)*4+1:i*4), (2,2))
        total += dot(a, a)
    end
    return total
end

function rvu(ar, n)
    total = 0.0
    for i in 1:n
        a = reshape(uview(ar, (i-1)*4+1:i*4), (2,2))
        total += dot(a, a)
    end
    return total
end

function rvs(ar, n)
    total = 0.0
    for i in 1:n
        a = reshape(uview(ar, (i-1)*4+1:i*4), Size(2,2))
        total += dot(a, a)
    end
    return total
end

function sa(ar)
    total = 0.0
    for i in 1:length(ar)
        total += dot(ar[i], ar[i])
    end
    return total
end

A = collect(1.0:40.0)
A2 = [(@SMatrix Float64[i i+1; i+2 i+3]) for i in 1:4:40]

@btime rv($A, 10)
@btime rvu($A, 10)
@btime rvs($A, 10)
@btime sa($A2)