Add documentation

[dlfivefifty]

There is almost no documentation or even code comments to explain what the code does. For example, I'm trying to use c_execute_tri_lo2hi but there is no explanation what basis the lo should be in.

[dlfivefifty]

I managed to reverse-engineer it:

julia> P = c_plan_rottriangle(5, 0.,0.,0.);

julia> F = zeros(5,5); F[1,2] = 1; F
5×5 Array{Float64,2}:
 0.0  1.0  0.0  0.0  0.0
 0.0  0.0  0.0  0.0  0.0
 0.0  0.0  0.0  0.0  0.0
 0.0  0.0  0.0  0.0  0.0
 0.0  0.0  0.0  0.0  0.0

julia> c_execute_tri_hi2lo(P, F); F
5×5 Array{Float64,2}:
 0.0   0.942809  0.0  0.0  0.0
 0.0  -0.333333  0.0  0.0  0.0
 0.0   0.0       0.0  0.0  0.0
 0.0   0.0       0.0  0.0  0.0
 0.0   0.0       0.0  0.0  0.0

julia> m,ℓ = 1,0;  Fun(t -> Fun(NormalizedJacobi(0,2m+1,0..1),[zeros(ℓ);1])(t) * 2^m*(1-t)^m, NormalizedJacobi(0,1,0..1))
Fun(NormalizedJacobi(0.0,1.0,0..1),[0.942809, -0.333333])

[MikaelSlevinsky]

I'm weighing all the different options for documentation such as: LaTeX, github.io, or the Wiki. LaTeX is good because it's lightweight (when the PDF isn't committed), but this may bloat the repository in time. Using GitHub.io is neat, but it will never look as good as what Documenter.jl produces for Julia packages. The automation behind the way it strips help text from package functions is great.

Maybe the best option is the wiki? It allows GitHub's flavour of markdown, which in turn allows html and thereby LaTeX for math. I don't think it add commits to the repository itself.

[MikaelSlevinsky]

Actually, looks like GitHub's markdown strips away scripts, so MathJax is probably off the table.

[dlfivefifty]

The wiki is a bad idea, it’s hard to edit and it’s better to use something inside the version control.

[MikaelSlevinsky]

I might hold off for a bit. Nothing's settled at this point. For example, the signature of the computational kernel ft_kernel_tri_hi2lo may change to specify the hi and lo m values, not just assuming m down to 0. Let me know if there's anything that needs urgent explaining.

[MikaelSlevinsky]

What do you think? http://mikaelslevinsky.github.io/FastTransforms/ The mobile use chops some of the formulas off, but perhaps that will be fixed in time

[MikaelSlevinsky]

Now that the structure is there, more documentation can be added