String negative indices?

[Erik Max Francis]

Steven D'Aprano wrote:

> In mathematics, well, maybe... certainly in the Real number system, there
> is no difference, and +0 and -0 are just two ways of writing the same
> thing. In the hyperreals, +0 and -0 are the same, but there are
> infinitesimals which are different, and signed. I don't know enough about
> the surreals to comment. In matrix maths, there are an infinite number of
> different matrices where all the elements are zero -- they are all
> distinct, different, zeroes.

What do you even mean by that?  By "matrix maths," do you just mean 
matrices whose elements are reals, or something else?

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