Which function has a jump discontinuity at x=0x=0x=0?
f(x)=xf(x) = xf(x)=x
Sign function (x/∣x∣x/|x|x/∣x∣)
f(x)=1/xf(x) = 1/xf(x)=1/x
f(x)=xf(x) = \sqrt{x}f(x)=x