It is the fifth letter of the Greek alphabet. Apparently first used by the Hungarian mathmetician Paul Erdos to denote a very small or insignificant quantity.
In this case it is a very small value, that is still representable using the floating point numbering system. It is used to determine if two numbers are approximately equal, because floating point numbers usually accumulate small rounding errors which make exact comparisons unlikely to suceeed. So here Epsilon is just about significant, and anything less than Epsilon is deemed to be insignificant
I guess all these Greek letters get used in maths because the Greeks were apparently rather good at it. So I am pretty sure I have no Greek ancestors. In any event If that is the only question you have about the above then you are a lot Greeker than me.
In this case it is a very small value, that is still representable using the floating point numbering system. It is used to determine if two numbers are approximately equal, because floating point numbers usually accumulate small rounding errors which make exact comparisons unlikely to suceeed. So here Epsilon is just about significant, and anything less than Epsilon is deemed to be insignificant
I guess all these Greek letters get used in maths because the Greeks were apparently rather good at it. So I am pretty sure I have no Greek ancestors. In any event If that is the only question you have about the above then you are a lot Greeker than me.