'almost' isn't defined/initialized in 'inverse_newton_sqrt' method

[jzakiya]

Hey Nathan,

Tried to run updated code benchmarks but it crashes because almost isn't defined/initialized in the inverse_newton_sqrt method.

Also, please include require 'benchmark/ips' just before running benchmark code to insure it has been loaded.

[jzakiya]

I replacd almost with result and that seemed to fix it, after testing the results compared to other methods.

def inverse_newton_sqrt(n)
  raise if n < 0
  return Math.sqrt(n).to_i if n < 1 << 53

  n_bits = n.bit_length
  exp = (n.bit_length - 1) & -2
  e_0 = ins_find_initial_exponent(n_bits)
  r   = ins_find_initial_r(n, e_0)
  e_bits, r, x = ins_core(n, e_0, r, exp)
  result = r * x >> (e_bits << 1) - (exp >> 1)
  #result += 1 if n > almost * almost + (almost << 1)
  result += 1 if n > result * result + (result << 1)
  result
end

[jzakiya]

Actually, you can drop the last line too.

def inverse_newton_sqrt(n)
  raise if n < 0
  return Math.sqrt(n).to_i if n < 1 << 53

  n_bits = n.bit_length
  exp = (n.bit_length - 1) & -2
  e_0 = ins_find_initial_exponent(n_bits)
  r   = ins_find_initial_r(n, e_0)
  e_bits, r, x = ins_core(n, e_0, r, exp)
  root = r * x >> (e_bits << 1) - (exp >> 1)
  root += 1 if n > root * root + (root << 1)
end