5 ms·

You are correct. But it really should be NaN, since 1/ε is positive infinity, whereas 1/-ε is negative infinity. Oh well :)

• Jach 8y ago
  JS just assumes the limit direction for you, so 1/0 is Infinity, but -1/0 is -Infinity. 0/0 at least is correctly NaN. (Edit: And I just verified against my memory, Matlab (or at least Octave) does the same thing. While Matlab might get characterized as being for the ivory tower, at least it's had a long history of being used for practical math applications within the tower. Edit2: And anyway this is the defined behavior for IEEE floats. Men of industry use industrial standards. :))
  • lightgreen 8y ago
    Moreover, 1/-0 is -Infinity. IEEE float has two zeros, positive and negative.
• mehrdadn 8y ago
  Nope, I'd disagree. Zero isn't an approximation of some epsilon, it's really just zero. It makes sense for the output sign to match the input sign.
  • gowld 8y ago
    What is the sign of 0? It's 0.
    • dahart 8y ago
      Parent was talking about the sign of the numerator. But... zero in IEEE 754 representation has a meaningful sign bit. 1/-0 = -inf.
    • GlitchMr 8y ago
      Or as IEEE 754 sees it (you can try this in your JavaScript REPL). >> 1 / 0 Infinity >> 1 / -0 -Infinity
• lightgreen 8y ago
  e is nearly 0, -e is nearly -0. So 1/0 is infinity, and 1/-0 is -infinity.