From: Robert Feldt <robert.feldt@...>
Date: 2013-03-07T16:55:54+09:00
Subject: Random#rand_inclusive?

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Hi,

Random#rand and Kernel#rand are exclusive i.e. they return a value >= 0.0
but <max if max is a Float. What if one wants a rand that is inclusive of
the max? Would any of the below approaches guarantee to give an inclusive
range?

class Random
  # Return a random number between 0 (inclusive) and max (inclusive).
  def rand_incl(max = 1.0)
    if Float === max
      rand(max+Float::EPSILON)
    elsif Integer === max
      rand(max+1)
    end
  end

  # Same but with other strategy
  def rand_incl2(max = 1.0)
    if Float === max
      num_floats = (max - min)/Float::EPSILON
      min + rand(1+num_floats.to_i) * Float::EPSILON
    elsif Integer === max
      min + rand(max+1-min)
    end
  end
end

Thanks in advance,

Robert Feldt

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Hi,<div><br></div><div>Random#rand and Kernel#rand are exclusive i.e. they =
return a value &gt;=3D 0.0 but &lt;max if max is a Float. What if one wants=
 a rand that is inclusive of the max? Would any of the below approaches gua=
rantee to give an inclusive range?</div>
<div><br></div><div><div>class Random</div><div>=A0 # Return a random numbe=
r between 0 (inclusive) and max (inclusive).</div><div>=A0 def rand_incl(ma=
x =3D 1.0)</div><div>=A0 =A0 if Float =3D=3D=3D max</div><div>=A0 =A0 =A0 r=
and(max+Float::EPSILON)</div>
<div>=A0 =A0 elsif Integer =3D=3D=3D max</div><div>=A0 =A0 =A0 rand(max+1)<=
/div><div>=A0 =A0 end</div><div>=A0 end</div><div><br></div><div>=A0 # Same=
 but with other strategy</div><div>=A0 def rand_incl2(max =3D 1.0)</div><di=
v>=A0 =A0 if Float =3D=3D=3D max</div>
<div>=A0 =A0 =A0 num_floats =3D (max - min)/Float::EPSILON</div><div>=A0 =
=A0 =A0 min + rand(1+num_floats.to_i) * Float::EPSILON</div><div>=A0 =A0 el=
sif Integer =3D=3D=3D max</div><div>=A0 =A0 =A0 min + rand(max+1-min)</div>=
<div>=A0 =A0 end</div><div>=A0 end</div>
<div>end</div><div><br></div><div>Thanks in advance,</div><div><br></div><d=
iv>Robert Feldt</div><div><br></div></div>

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