Here is a real world example: a = Float64[-159.5; -158.5; -39.5;;] typeof(a) Matrix{Float64} (alias for Array{Float64, 2}) size(a) (3, 1) b = vec(a) b = Float64[-159.5, -158.5, -39.5] typeof(b) Vector{Float64} (alias for Array{Float64, 1}) size(b) (3, ) It seems that Julia considers them to be di…

a = [1; 2; 3] b = [1, 2, 3] println(typeof(a)) println(typeof(b)) println(a == b) shows Vector{Int64} Vector{Int64} true I’m confused.

[image] leon: b = Float64[1, 2, 3] Sorry for the confusion. Maybe that’s not a good example. Note I have modified the original post. In my cases, when it is not working, below is often the type: typeof(a) = Matrix{Float64} After I do an b =vec(a), it will work and now its type is as below: …

For two dimensions we have a1 = [[1, 2], [3, 4]] println(typeof(a1)) b1 = [[1, 2]; [3, 4]] println(typeof(b1)) a2 = hcat([1, 2], [3, 4]) println(typeof(a2)) b2 = vcat([1, 2], [3, 4]) println(typeof(b2)) println(b2 == b1) with Vector{Vector{Int64}} Vector{Int64} Matrix{Int64} Vector{Int64} true …

I found this text which probably provides the detailed motivation for the difference between one-column matrices and vectors: https://github.com/toivoh/Julia-Design-Thoughts/wiki/Row-vectors#motivation

We would need a rather hypothetical type system to equate n x 1 matrices with column and 1 x m matrices with row vectors. So compromises have to be made, probably.

Many thanks for the very helpful replies! BTW, how can I create a size(3, 1) matrix in Julia? I just tried. Either , or ; will result in a vector with the size of (3,) directly. b1 = [1; 2; 3] b2 = [1, 2, 3] If I created m by n matrix called B first and do b = B[:,1], it will give me a vector a…

[image] leon: BTW, how can I create a size(3, 1) matrix in Julia? I saw it in your code: julia> b1 = [1; 2; 3;;] 3×1 Matrix{Int64}: 1 2 3

Many thanks! Wow, I thought the double semicolons at the end were by accident. They were actually intentional.

[image] goerch: So compromises have to be made, probably. Yeah… I tried to follow some GitHub issues on the original design of these, but they are pretty technical. What’s clear is that everyone involved had clear knowledge on what Matlab does, and they agreed that having that distinction is …

Unfortunately, this design has been a major problem to my programs. If having data in vector is so important, what harm will it do to design their programs by first converting any applicable 1-column matrix into a vector internally? “Elrod post demonstrating that some compiler optimizations are ea…

1-Column matrix vs. Vector

New to Julia

StefanKarpinski November 14, 2021, 1:32am 17

I wrote a long post explaining many motivations for distinguishing these as types when you brought it up previously:

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1-Column matrix vs. Vector

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