(exp(b₁⋅(x - x₀)) + 1)            (exp(b₁⋅(x</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>    </span>
<span class="r-out co"><span class="r-pr">#&gt;</span>                      ⎤</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>                      ⎥</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>                      ⎥</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>                      ⎥</span>
<span class="r-out co"><span class="