var inf = 1/0    # same as: Inf
var nan = 0/0    # same as: NaN

var exprs = [
  "1.0 / 0.0", "-1.0 / 0.0", "0.0 / 0.0", "- 0.0",
  "inf + 1", "5 - inf", "inf * 5", "inf / 5", "inf * 0",
  "1.0 / inf", "-1.0 / inf", "inf + inf", "inf - inf",
  "inf * inf", "inf / inf", "inf * 0.0", " 0 < inf", "inf == inf",
  "nan + 1", "nan * 5", "nan - nan", "nan * inf", "- nan",
  "nan == nan", "nan > 0", "nan < 0", "nan == 0", "0.0 == -0.0",
]

exprs.each { |expr|
  "%15s => %s\n".printf(expr, eval(expr))
}

say "-"*40
say("NaN equality: ",        NaN ==  nan)
say("Infinity equality: ",   Inf ==  inf)
say("-Infinity equality: ", -Inf == -inf)

say "-"*40
say("sqrt(-1)   = ",   sqrt(-1))
say("tanh(-Inf) = ", tanh(-inf))
say("(-Inf)**2  = ",  (-inf)**2)
say("(-Inf)**3  = ",  (-inf)**3)
say("acos(Inf)  = ",  acos(inf))
say("atan(Inf)  = ",  atan(inf))
say("log(-1)    = ",    log(-1))
say("atanh(Inf) = ", atanh(inf))