an class="n">Y_R</span><span class="p">(</span><span class="n">pp</span><span class="p">)</span> <span class="o">=</span> <span class="nb">SQRT</span><span class="p">(</span><span class="n">X_X</span><span class="p">(</span><span class="n">pp</span><span class="p">)</span><span class="o">*</span><span class="n">X_X</span><span class="p">(</span><span class="n">pp</span><span class="p">)</span> <span class="o">+</span> <span class="n">X_Y</span><span class="p">(</span><span class="n">pp</span><span class="p"