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"Mathematicians don't use square brackets for functions"

Not true at all:

1) Operators acting on a distribution: E[X], Var[X], Cov[X,Y]

2) Square brackets are used in nested parentheses to avoid confusion: [1(2 + 3) + 4]/5

3) Functionals: L[f] for lagrangian

The main reason why [] isn't used as frequently as () is because most domains interpret the square brackets to mean something special. For example:

1) [x] is often used to denote floor(x)

2) [i=j] is used to denote the kronecker delta




On point (2) -- In four years of being a math major, I don't think a single professor ever used brackets in that situation, only additional parentheses.


I'm inclined to agree that it's use would be uncommon, I've not encountered it in 30 odd years of reading papers and talking math (or rather I don't recall noticing it's use).

What I must point out is you make a weak case based on myopia- for example; in 15 years of working with tens of thousands of hours of high resolution radiometrics I've never once met and talked to a dendrochronologist who's looked at the radiometric signature of individual bands of Japanese pine trees.

It's my understanding that such beasts do exist.


Another math major here (in my final year). My professors routinely use square brackets after the second or third level of bracket nesting.

I think it must depend on the professor/university.


It's common in engineering. I like it because it makes matching parenthesis much easier.




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