Docs for I

[JaredCrean2]

In #18247 , the I variable was mentioned, but (as far as I can see) there are no docs for it.

Just for clarification:

julia> a = rand(3,3)
3x3 Array{Float64,2}:
 0.125392   0.162639  0.0208102
 0.0438847  0.253112  0.817613 
 0.877253   0.27941   0.94262  

julia> I + a
3x3 Array{Float64,2}:
 1.12539    0.162639  0.0208102
 0.0438847  1.25311   0.817613 
 0.877253   0.27941   1.94262  

[tomaklutfu]

http://docs.julialang.org/en/release-0.4/manual/linear-algebra/?highlight=identity#the-uniform-scaling-operator

[JaredCrean2]

Indeed, I did not see that. However, searching for Base.LinAlg.I returns no results, and the REPL help says that it is a UniformScaling of some kind, but not exactly what it is.

[stevengj]

help?> I
search: I IO if is Int in im Inf isa Int8 inv IPv6 IPv4 Int64 Int32 Int16 info imag ifft idct Inf64 Inf32 Inf16 Int128 issym isqrt isodd isnan isinf isdir irfft

  I

  An object of type UniformScaling, representing an identity matrix of any size.

This is a bit too terse to be useful, though.

[kshyatt]

@stevengj I agree! This would be a great first doc PR for someone who wants to make one.

[sudk1896]

@kshyatt: I'd like to take a stab at this. What do I have to do here ? Thanks.

[kshyatt]

Hi @sudk1896! That's great to hear. My suggestion would be to go into the docs/stdlib/numbers.rst to see how we've documented other constants (e.g. pi and e). Following that template, you could add a docstring for I to docs/stdlib/linalg.rst and then build the docs, commit your changes, and open the PR. Let me know if you would like more detailed instructions!

[sudk1896]

@kshyatt: AFAIK, I have to edit the doc-strings in the source and not the .rst since the .rst are compiled automatically from the source. Also, which modules can I find the constants pi and e and I implemented in ? (I'm in the process of another doc-fix, learnt the whole workflow).
The docs don't include the links to the files that the functions are actually implemented in.
Also, Shouldn't the docs point to the .jl files that the functions are implemented in instead of the .rst files, since that is where the doc-strings are originally generated from ?
Most of the python repos that I contributed to, did this.
Thanks.

[stevengj]

I (and its docstring) are in base/linalg/uniformscaling.jl (see #6472). Things like pi are in base/irrationals.jl.

[vsartor]

Given that the commit 573467a already added some examples to the docstring (specifically here), is there still a need for more documentation or should this be closed?

[andreasnoack]

I think it is fine now that the example has been added.