[julia-users] Re: using subscripts \_1, \_2, ... as field names

[ggggg]

I'm no macro expert, but I think one could parse the variable names in a 
macro to enable Tim Wheeler's as @subind Σ₁₁ to get Σ[1,1]

[julia-users] Re: using subscripts \_1, \_2, ... as field names

[Davide Lasagna]

I see that most of the latex symbols representing digits cannot be used as 
variable/field name, (e.g., \msansone, \mbfone). I guess this is a 
deliberate choice, made to prevent disasters from happening when this kind 
of notation is over abused. I have to say though that there are probably a 
couple of cases where it would be useful, like the one I mentioned. 



On Tuesday, May 10, 2016 at 9:56:16 AM UTC+1, Davide Lasagna wrote:
>
> Hi, 
>
> I have a custom type representing a bordered matrix (a big square matrix, 
> bordered by two vectors and a scalar in the bottom right corner), where the 
> four blocks are stored in separated chunks of memory. I would like to call 
> the fields of my type using subscripts \_1\_1, \_1\_2, ... so that I can 
> nicely access them as A.11, A.12, ... However, it seems that subscripts 
> (and superscripts) with digits can't be used for variable names, resulting 
> in a syntax error.  Subscripts with letters work fine. 
>
> Any thoughts on this? 
>

[julia-users] Re: using subscripts \_1, \_2, ... as field names

[Tim Wheeler]

I would love to see a₁ automatically call getindex(a, 1). It would make 
math easier.

I'd love to be able to write:

b = μ₂ + Σ₁₂*(a₁ - μ₁)/Σ₁₁
Λ = Σ₂₂ - Σ₁₂*Σ₁₂/Σ₁₁

for μ::Vector{F<:Real}
and Σ::Matrix{F<:Real}

Σ could be accessed via Σ₁₁ to get Σ[1,1]. Of course this breaks down with 
digits larger than 9, but you probably don't want to be using this feature 
for such large values.




On Tuesday, May 10, 2016 at 1:56:16 AM UTC-7, Davide Lasagna wrote:
>
> Hi, 
>
> I have a custom type representing a bordered matrix (a big square matrix, 
> bordered by two vectors and a scalar in the bottom right corner), where the 
> four blocks are stored in separated chunks of memory. I would like to call 
> the fields of my type using subscripts \_1\_1, \_1\_2, ... so that I can 
> nicely access them as A.11, A.12, ... However, it seems that subscripts 
> (and superscripts) with digits can't be used for variable names, resulting 
> in a syntax error.  Subscripts with letters work fine. 
>
> Any thoughts on this? 
>