What does "./" mean?

Questions
1

I’m very new to mathimatica. Someone sent me a program, as a suggestion for a problem, but despite innumerable searchs I can’t figure out what “./” means in this context: "

Switch[i - j, -1, -1./h^2, 0, u[[j]] + 2./h^2, 1, -1./h^2, _, 0]

Any help would be appreciated.

2

In the code shown ./ is not single symbol. As an example, 2./h^2 reads 2 divided by h squared. The decimal after the 2 tells Mathematica that 2 is an approximate number. 2 without the decimal would represent an exact number.