In many programming languages, you do need the spaces to avoid ambiguity. “x-y” could be a variable, or it could be subtracting variable y from variable x.

Most professionals in mathematics and the sciences use LaTeX when creating professional documents with mathematical formulae. LaTeX automatically includes a small amount of space around math symbols, which seems to be a fairly standard convention. Obviously, if you are coding, you would follow whatever convention exists (if there is one).

MikeS - I found that Chicago Manual of Style, and checked in the mathematics section but couldn’t find that part you quoted. My internet blindness must be acting up again.

Bah. I should have known. (The interesting thing is that old-fashioned FORTRAN worked precisely the opposite way: “DO 10 I = 1.10” (a typo for “DO 10 I = 1,10”, which begins a counted loop setting I from 1 to 10, inclusive) creates a variable DO10I and assigns it the value 1.10, because FORTRAN lexers ignored all spaces outside of quoted strings.)