⋅exp(b₁⋅(x - x₀))   </span>
<span class="r-out co"><span class="r-pr">#&gt;</span>    ⎢            0                                   ──────────────────────────   </span>
<span class="r-out co"><span class="r-pr">#&gt;</span>    ⎢                                                                       2     </span>
<span class="r-out co"><span class="r-pr">#&gt;</span>    ⎢                                                 (exp(b₁⋅(x - x₀)