`SVector`, `StructOfArrays`, etc... about climatemachine.jl HOT 2 CLOSED

For newcomers to this issue, the idea is as follows:
Say we're using a really simple time stepper to update the velocity of the particles stored in a vector v. To start out, we could initialize the vector v as:

v = zeros(Float64, 3, nparticles)
dvdt = rand(3,3)
dt = 0.5

Then the time stepper could be written as:

for i in eachindex(v)
  v[1, i] += dvdt[1] #X coordinate of velocity
  v[2, i] += dvdt[2] #Y coordinate of velocity
  v[3, i] += dvdt[3] #Z coordinate of velocity
end

We could collapse this with another for-loop like

for i in eachindex(v)
  for pos in 1:3
  v[pos, i] += dvdt[pos] #X coordinate of velocity
end

but in Julia, we can do better. Suppose instead we initialize our array of velocities as precisely that: an array of velocity vectors. Note that we are using SVectors so the compiler will make our tiny loops unroll and be fast.
We would initialize as

using StaticArrays
v = zeros(SVector{3, Float64}, 3, nparticles)
dvdt = SVector{3, Float64}(rand(3))
dt = 0.5

Then we can write our loop as

for i in eachindex(v)
  v[i] += dvdt * dt #forward euler step of velocity
end

This works because + is defined on two vector types and * is defined between scalar and vector types! Way cool!

from climatemachine.jl.

Right now we are waiting for JuliaGPU/CUDAnative.jl#340 before we can start creating device arrays.

from climatemachine.jl.