Consider the code below. function dummy() A = zeros(2,2) for i=1:2 for j=1:2 A(i,j) = rand() # should be A[i,j] end end return A end It returns julia> A=dummy() A (generic function with 1 method) which is very weird, since in the REPL writing A(i,j) in…

Never mind! I figured it out. It’s the inline function definition syntax tripping me up. A(i,j) = rand() is defining a function that maps its 2 args to a random number. This is a nasty “gotcha” for ex Matlab prorgammers to be aware of!

You’re not the only one: [image] No error when using () for indexing inside a loop General Usage I accidentally came across this observation, when trying to create a symmetric matrix. julia> versioninfo() Julia Version 1.1.0 Commit 80516ca202 (2019-01-21 21:24 UTC) Platf…

Using the same syntax for indexing as function calls is a bug in the Matlab syntax. (It leads to strange behavior in edge cases.) At least in Julia, when things go wrong it’s because of a programmer error.

This may get me expelled from class, but occasionally I define this… (A::Array)(ijk...) = A[ijk...] Obviously this is a terrible idea! But it shouldn’t break valid Julia code, and would turn the above loop into an error. Which which can be useful on the first pass of trying to hack some Matlab scr…

Yeah, we have a nice error message when you try to access A(i, j), but trying to assign into it like this is a much harder case to catch — namely because it actually means something different!

A(i,j) instead of A[i,j] leads to weird behavior

General Usage

bennedich January 28, 2019, 10:02pm 3

You’re not the only one:

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A(i,j) instead of A[i,j] leads to weird behavior

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