an> <span class="o">=</span> <span class="n">mse</span><span class="p">(</span><span class="n">ref</span><span class="p">,</span> <span class="n">predictions</span><span class="p">)</span>
    <span class="n">e</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">abs</span><span class="p">(</span><span class="n">mean_error</span><span class="p">(</span><span class="n">predictions</span><span class="p">,</span> <span class="n">ref</span><span class="p">,</span> <sp